What Is a 'Wrong Ball,' and What's the Penalty for Playing One?

Golf Rules FAQ

Man walking up to golf ball
Before hitting the ball, make sure it is yours - or you might face a wrong ball penalty. Cavan Images/Iconica/Getty images

You and your buddy tee off on a hole and both hit into the rough. You reach the golf balls first and play your stroke. But when your buddy checks out the other ball, he discovers some bad news: You accidentally hit his golf ball. You played the wrong ball. Whoops.

What's the penalty? First, let's define "wrong ball."

'Wrong Ball' Definition in the Rules of Golf

So what, exactly, is a wrong ball in golf? This is the official definition of the term as it appears in The Rules of Golf, written and maintained by the USGA and R&A:

Any ball other than the player’s:
*Ball in play (whether the original ball or a substituted ball),
*Provisional ball (before it is abandoned under Rule 18.3c), or
*Second ball in stroke play played under Rules 14.7b or 20.1c.
Examples of a wrong ball are:
*Another player’s ball in play.
*A stray ball.
*The player’s own ball that is out of bounds, has become lost or has been lifted and not yet put back in play.

So, basically, before you play any stroke, make sure the ball you are about to hit is yours! Duh! This is why the Rules of Golf also state that it is every golfer's obligation to write or draw onto the golf balls they are using some kind of identifying mark. That way if you and your buddy (or fellow-competitor or opponent) are using the same make and model of golf ball, you'll be able to tell them apart.

Still, mistakes do sometimes happen. Maybe your ball is in a spot that makes seeing the identification mark you put on it difficult; maybe you're just rushed and assuming a ball is yours.

If you do make a mistake and hit a golf ball that isn't yours, what happens? What's the penalty?

The Penalty for Playing a Wrong Ball

In almost all cases, playing the wrong ball results in loss of hole in match play and a two-stroke penalty in stroke play. (The rare exception involves swinging at a wrong ball that is moving in water inside a water hazard.)

In stroke play, the offender must go back and replay any strokes with the correct ball. Failure to correct the mistake before teeing off on the following hole can result in disqualification.

The player whose ball was incorrectly played by a competitor or partner should drop a ball as close to the original spot as can be determined.

In the rulebook, wrong ball situations are covered in Rule 6-3c, so read that rule for the full story.