What happens if you hit the wrong ball in golf?

The situation

You think you've found your ball in the rough, play it, and then realise it was someone else's. Or you play a ball with the right brand but the wrong number.

The rule

Under Rule 6.3c (stroke play), playing a wrong ball — any ball other than your ball in play — results in a 2-stroke penalty. The strokes made with the wrong ball do not count. You must then find your correct ball and play it, adding the 2 penalty strokes. If you can't find your correct ball after playing the wrong one, it's still considered lost — take stroke-and-distance relief on top of the 2-stroke penalty. In match play (Rule 6.3a), the first player to play a wrong ball loses the hole.

Real example

Your ball and your partner's are both Titleist Pro V1s in the same patch of rough. You play one — it's theirs. 2-stroke penalty. You must find your own ball (or take lost ball relief if it's not found) and complete the hole adding those 2 strokes.

What to do on the course

• Always mark your ball with a unique mark before the round — a dot, initials, or line
• Identify the ball before playing it: check brand, number, and your personal mark
• In stroke play, if you're unsure whether a ball is yours, don't play it until you're sure
• If you've made a stroke with the wrong ball, don't play any more strokes with it — stop as soon as you realise and correct the situation

Penalty

2-stroke penalty in stroke play. Loss of hole in match play.