Rule 27-1

Ball Lost or Out of Bounds
If a ball is lost or is out of bounds, the player must play a ball, under penalty of one stroke, as nearly as possible at the spot from which the original ball was last played (see Rule 20-5).
Exceptions:
1. If there is reasonable evidence that the original ball is lost in a water hazard, the player must proceed in accordance with Rule 26-1.
2. If there is reasonable evidence that the original ball is lost in an obstruction (Rule 24-3) or an abnormal ground condition (Rule 25-1c) the player may proceed under the applicable Rule.
PENALTY FOR BREACH OF RULE 27-1:
Match play ? Loss of hole;
Stroke play ? Two strokes.
<< back to the rules of golf