Shiai (kendo matches) are a way of exhibiting the principles of kendo. The competitors face each other with all their energy, yet with mutual respect, as expressed through rei-ho. In theory, the kendo should be similar to normal keiko, but a match is conducted with a great deal more formality, including a marked court, the presence of judges, a time limit, and the keeping of scores.

Matches are conducted within a square or rectangular court (shiai-jo) which is nine to eleven meters on a side. The center of the court is marked with an "X" on the floor. Two lines (kaishi-sen), approximately 1.4m to the right and left of the center, mark where the players position themselves when drawing their shinai and when continuing and ending the match.

Two players compete, each wearing a strip of cloth (mejirushi) on the back, one red and the other white.

There are three shinpan (referees) on the court: the shushin (chief referee) and two fukushin (sub-referees). The shushin is responsible for administering the match and making match pronouncements. All three referees are responsible for determining yuko datotsu (valid points) and prohibited acts.

Each referee holds two flags (shinpan-ki), one red and one white. A yuko datotsu is signaled by raising the flag corresponding to the player who made the strike. If at least two referees agree on the yuko datotsu, the match is stopped and a point is awarded to the player.

Most tournaments are conducted with sanbon shobu (three point matches). In sanbon shobu, the player who scores two points first is the winner. If the match period expires and only one player has scored a point, that player wins the match. The time limit for championship matches (e.g. the AUSKF Championships) is five minutes. For local tournaments, it is generally shorter, typically three minutes.

If a winner has not been determined by the end of the match period, an encho (extension) of the match is allowed. During encho, the first player to score a point wins the match. For championship matches, the encho period is unlimited. In local tournaments, the encho is typically limited to one or two minutes; if no point is scored the match may be decided by hantei (judges selection of the winner). Typically semi-final and final matches have unlimited encho and no hantei.

Shiai rei-ho is similar to basic rei-ho, with the addition of court formalities.

• The court must be respected as the area where matches are conducted. If possible, do not enter the court unless actually competing in it, for example go around the court rather than walking through it or across a corner of it. Especially, do not walk on the court with shoes.
• Before entering the court to compete, be physically and mentally prepared for the match. Exhibit kigurai (confidence, bearing).
• Together with the opponent: enter the court to a point three big steps from the kaishi-sen (starting line), perform ritsu-rei, bring the shinai to the tai-to position, starting from the right foot take three big steps to the kaishi-sen, draw the shinai, and go down into the sonkyo position.
• When the shushin says "hajime," stand up and start the match.
• Whenever the shushin stops the match ("yame"), return to the kaishi-sen.
• When the match is over, return to the kaishi-sen and wait for the shushin's final command. With the opponent: go down into the sonkyo position, noto (put away the shinai), stand up, starting from the left foot take five small steps back, perform ritsu-rei, and leave the court by walking several steps backwards.
• If there is a break in the match, for example if one player must fix their equipment or the shinpan have a gogi (conference), both players kamae at the kaishi-sen, noto while remaining standing, then retreat to the border of the court. While waiting, the player remain in the sonkyo or seiza position inside the court, unless one must leave to retrieve a piece of equipment such as a new shinai.
• In case of fusen-gachi (win by default, or "no show"), the player proceeds to the kaishi-sen in the same manner as if an opponent were present, takes the sonkyo position, and stands. After the shushin pronounces "shobu-ari", the player performs sonkyo, noto, etc., in the same manner as if an opponent were present.

See also kihon shiai below.

For yuko datotsu, the following elements must be present:

1. accurate strike or thrust to the datotsu bui (valid strike) area of the men, kote, do, or tsuki
2. the strike uses the datotsu bu (effective cutting) area of the shinai, with the correct hasuji (blade angle)
3. kisei (fullness of vigor and spirit)
4. shisei (correct posture)
5. zanshin (mental and physical alertness against the opponent's counter-attack)

Most shinpan also take into account:

1. the sound of the strike
2. ki-ken-tai-no-ichi: spirit, shinai, body are one
3. kime: 100% commitment to the point, putting everything into the point

After being awarded, a yuko datotsu may be revoked under the following circumstances:

1. Lack of zanshin
2. Displaying excessive force
3. Exaggerated gestures or display after datotsu

The following prohibited acts result in the offending player losing the match.

1. Drug abuse
2. Insulting the opponent or referees
3. Use of disallowed protectors
4. Incapacitating the opponent such that he or she is unable to continue

The following prohibited acts result in the offending player receiving a hansoku (foul). When a player receives two hansoku, the opposing player is awarded one point.

1. Stepping outside the court
2. Dropping one's shinai or losing control of it for more than a moment
3. Tripping the opponent or sweeping his or her legs
4. Unfairly pushing the opponent outside the court
5. Request for suspension of the match without justifiable reason
6. Putting one's hand on the opponent or holding the opponent
7. Holding or trapping the opponent's shinai
8. Touching one's own shinai on its edge
9. Intentionally putting one's shinai on the opponent's shoulder
10. Intentionally wasting time
11. Unfairly doing tsuba zeriai
12. Unfairly making a strike or thrust
13. Aftering having fallen on the floor, lying on one's face without countering the opponent

The shushin is responsible for making match pronouncements:

• hajime command to start/continue the match. This starts/resumes the clock for timed matches.
• yame command to stop the match and return to the kaishi-sen. This stops the clock for timed matches.
• men ari, kote ari, do ari, tsuki ari same as yame but also announces a yuko-datotsu
• nihon me same as hajime, said after the first point of the match is awarded
• shobu same as hajime, said after the score is one point each
• shobu ari announces the end of the match, the winning side is indicated by the raised flag
• encho, hajime announces the start of the match extension period
• wakare, hajime command to separate, issued by the shushin when the players are inactive too long in tsubazeriai. On the "wakare" command the players separate where they are (they do not return to the kaishi-sen) and the clock does not stop. On "hajime" the players resume the match.
• hansoku ikkai announces the first hansoku. Said while the shushin holds an index finger up to the offending player.
• hansoku nikai, ippon ari announces the second hansoku and awards a point to the opponent ("hansoku nikai" is said while the shushin holds two fingers up to the offending player, "ippon ari" is said while the flag is raised in the yuko-datotsu position)
• hantei command by the shushin to the fukushin to show their match decision
• hikiwake announces the end of a match where the result is a tie
• gogi announces a shinpan discussion will be held in the center of the shiai-jo
• sosai simultaneous hansoku by both sides (the hansoku offset each other and have no effect on scoring)
• torikeshi revoking of yuko-datotsu

In kihon shiai, two competitors are judged on their ability to perform rei-ho and uchikomi-geiko. The competitors each have a motodachi partner; thus there are two pairs of participants in the court.

The competition focuses on the following areas.

• Rei-ho, judged on the following:
  • shisei (posture) and kigurai (confidence, presence, bearing)
  • ritsu-rei
    - entering the shiai-jo to the proper distance from the center
    - posture and stance, feet together
    - shinai position and angle (sage-to)
    - correct bow (sogo-no-rei), including angle and eyes
  • movement to sonkyo
    - shinai position and angle (tai-to)
    - three large steps to the line, starting from right foot
    - sonkyo: posture, left hand one fist in front of the tanden
  • kamae
• Kiri-kaeshi, judged on the same points as uchikomi-geiko (see below) plus the following:
  • correct tai-atari (body collision), no pushing with the hands
  • 9 sayu-men strikes
    - start and end on the right
    - 4 forward strikes with smooth transition to 5 back
    - proper hasuji (angle of cut) on swing and cut
    - hands go through the jodan position, not circling around the head or staying in front of the face or shoulders
  • left hand in center of body when striking
• Uchikomi-geiko, judged on the following:
  • kiai (clearness, intensity, enunciation on each strike)
  • furi-kaburi (big motion swings, hands go through jodan, shinai tip does not drop excessively)
  • proper posture
  • proper ma-ai (distance) at kamae and each strike
  • striking with monouchi, with proper te-no-uchi and arm extension
  • proper footwork, right foot never behind the left
  • turning in the proper direction
  Note: the uchikomi sequences are pre-announced by the shushin and typically consist of some combination of men, kote, do, kote-men, kote-do, etc.
• Kakari-geiko, judged on the same points as uchikomi-geiko (see above)
  Note: in kakari-geiko the player hits the openings presented by the motodachi
• At Norwalk Dojo, kihon shiai is conducted as sanbon-shobu (three point match). Each is decided by hantei. For early beginners, the first point is after rei-ho up to sonkyo and kamae, the second point is after four men strikes, as is the third point (if necessary). For advanced beginners, points will be after uchikomi, kirikaeshi, and kakari-geiko, as decided by the shushin.

• The shinpan have the responsibility to see that shiai are fairly and safely conducted. They must clearly and promptly signal their own decisions as well as acknowledge the signaling of the other shinpan.
• Before taking their positions for the first time in the court, the three shinpan line up on the side of the court opposite the shomen and/or the official's table, about one meter inside the court, with the shushin (chief referee) in the center. After rei (commanded by the shushin), the two fukushin (sub-referees) walk straight to their starting positions, about one meter inside the court. The shinpan form a triangle with the shushin at the apex and the fukushin in line with the shushin and their respective kaishi-sen.
• The shinpan attempt to maintain their relative positions around the players during the match by moving to maintain the triangle configuration. This is to ensure each shinpan has a clear view of the various points which may be struck, as well as a clear view of the other shinpan.
• The shushin holds the red shinpan-ki (flag) in the right hand, the fukushin hold the red shinpan-ki in the left hand.
• The shinpan signal using the shinpan-ki as follows:
  • yuko-datotsu: raise the appropriate shinpan-ki 45 degrees up from the shoulder.
  • denial of yuko-datotsu or hansoku: repeatedly criss-cross the shinpan-ki in front of the lower body
  • abstention: hold the shinpan-ki crossed in front of the lower body
  • yame: hold both shinpan-ki straight up overhead
    Note: normally only the shushin announces "yame", but if safety requires it the fukushin may also say "yame"
  • hansoku: hold the appropriate shinpan-ki 45 degrees down from the shoulder
  • hikiwake: hold the shinpan-ki crossed in front above the head
  • wakare: the shushin holds both shinpan-ki straight forward, on "hajime" the shinpan-ki are lowered
  • gogi: put both shinpan-ki in the right hand and raise the right hand straight up
  • sosai: hold both shinpan-ki 45 degrees down from the shoulder
  When not signaling, the shinpan-ki are held down at the sides. Return the shinpan-ki to this position when the shushin finishes making the appropriate pronouncement, or when denial is acknowledged among the shinpan.
• Other handling of the shinpan-ki:
  • When entering and leaving the court, hold in the right hand both shinpan-ki rolled together with the red shinpan-ki on the outside.
  • when rotating positions, hold both shinpan-ki in the right hand
• Jogai (out of bounds) shall be called if one foot is totally outside the boundary line, the body is supported by a part of the body or the shinai outside the boundary line, or if the player has fallen and part of the body is outside the boundary line.
• For hantei, the first consideration is skill (the player who made datotsu nearly equal to yuko-datotsu), and second is attitude in shiai (the player who was predominant in posture and movements).