1. The ball has a diameter of 40 mm and a weight of 2.7 g. (This change will take effect from 1 October 2000. From that date the 40 mm ball must be used in international competitions but Associations may, at their discretion, continue to use the 38 mm ball for domestic competitions).

2. A player obstructs the ball if he, or anything he wears or carries, intercepts it when it is moving towards the playing surface and has not passed beyond his end line, not having touched his court since last being struct by his opponent. (New wording is in bold).

Regulations For International Competitions

1. A racket can not be changed during a match unless it is accidentally damaged so badly that it can not be used.

2. There may be up to three advertisements on the front and sides of a shirt, having a total area of not more than 200 cm². (At present the limit is 160 cm²).

3. The referee can disqualify for the remainder of a competition a coach who has been sent away from the playing area twice during that competition.

4. In World Championships doubles events, both players must be from the same association.

Source : ITTF