What is a pitcher not allowed to do to the ball, or to the batter?
A · Advanced · Pitching and game management · 8 of 9A pitcher may not spit on the ball, rub it on their clothing, put any foreign substance on it, scuff it or carry such a substance at all. The penalty is ejection. A pitcher may not throw at a batter on purpose either: the umpire may eject the pitcher, and the manager too, or warn both teams.
How it works
- The ball: the pitcher shall not "apply any foreign substance of any kind to the ball" or "deface the ball in any manner".
- Also banned: rubbing the ball on the glove, body or clothing, and blowing, coughing or spitting on the ball, hand or glove.
- Carrying it: having any foreign substance on the person is itself a violation.
- Penalty: ejection. The umpire may warn instead where there was no intent to alter the ball.
- Hand to mouth: not while on the rubber or in the dirt circle of the mound. A warning first, then a ball each time.
- Cold weather: the umpire may allow pitchers to blow on their hands.
- Anyone: a player who discolours or damages the ball is removed from the game and suspended for ten games.
- Throwing at the batter: if judged intentional, the umpire may eject the pitcher, or the pitcher and manager.
- Or warn: both teams may be warned that the next such pitch means ejection of the pitcher and the manager.
- Both hands: a pitcher may not pitch right-handed and left-handed to the same batter in one turn at bat.
- The glove: not white or grey, and nothing distracting on it.
The glossary has the pitcher, the pitch, the ball, the umpire, the batter and the pitcher's mound.
Tricky cases
A pitcher licks their fingers on the rubber and then wipes them dry. Is that allowed?
No. Going to the mouth is not allowed on the rubber or inside the mound circle. The first time brings a warning.
An umpire finds a sticky substance on the pitcher's glove. The pitcher says it was never used. What follows?
Ejection. Having a foreign substance on the person or in possession is a violation in itself.
A pitch hits a batter after two home runs in a row. Is the pitcher ejected automatically?
No. It depends on the umpire's judgement of intent. The umpire may eject, or warn both teams.
A manager comes out to argue a warning for throwing at a batter. Allowed?
No. Nobody may come onto the field to argue a warning issued by the umpires.
Why the rule exists
A ball that is wet, sticky or scuffed on one side moves in the air in ways a clean ball cannot, and a batter cannot see it coming. A hard ball thrown at a head can do serious harm: the rule book calls it "unsportsmanlike and dangerous" and tells umpires to act "without hesitation".
Where it differs
| Where | What changes | Source |
|---|---|---|
| Foreign substance or defacing | Ejection | WBSC Baseball Rule 13.6.5 |
| Hand to mouth on the mound | Warning, then a ball | WBSC Baseball Rule 13.6.4 |
| Damaging the ball, any player | Removal and a ten-game suspension | WBSC Baseball Rule 3.1 |
| Throwing at a batter | Ejection or a warning to both teams | WBSC Baseball Rule 13.6.7 |
From the rule book
World Baseball Softball Confederation, Official Rules of Baseball (2025-2026 edition), Rules 3.1, 3.4.4, 13.6 and 13.9. Checked 14 October 2026. Official document: WBSC Official Rules of Baseball 2025-2026 (PDF).