Activities Sports & Athletics One Ball Rule: Do the Rules of Golf Prohibit Changing Balls During a Round? The 'one ball condition,' and does it apply to you? Share PINTEREST Email Print Kim Schandorff/Moment/Getty Images Sports & Athletics Golf Basics History Gear Golf Courses Famous Golfers Golf Tournaments Baseball Basketball Bicycling Billiards Bodybuilding Bowling Boxing Car Racing Cheerleading Cricket Extreme Sports Football Gymnastics Ice Hockey Martial Arts Professional Wrestling Skateboarding Skating Paintball Soccer Swimming & Diving Table Tennis Tennis Track & Field Volleyball Other Activities Learn More By Brent Kelley Brent Kelley is an award-winning sports journalist and golf expert with over 30 years in print and online journalism. our editorial process Brent Kelley Updated April 21, 2018 Some golfers believe that it is "illegal" under the rules to change the make and model of golf ball you are playing during a round. That, in other words, you have to end your round of golf using the exact same type of golf ball with which you began it. Is that true? No. There is nothing in the Rules of Golf that prevents a golfer from switching to a different brand of golf ball (i.e., from a Titleist to a Bridgestone) on every hole on the course - so long as the change is made between the play of holes rather than during the play of a given hole. However, there is something in the Rules of Golf that says a tournament committee can impose such a rule. Committees Can Impose the 'One Ball Condition' It's called the "one ball condition," perhaps more commonly known as the "one ball rule." As you probably know, all Tour events are played under the "one ball rule." And any rules committee may adopt the "one ball rule" for its competitions. The "one ball condition" requires the player to use the exact same brand and type of ball throughout the round. For example, if you tee off the first hole with a Titleist Pro V1x, then that's what you must play throughout the round. You may not switch to any other brand of ball, nor even to any other type of Titleist ball. You started with the Pro V1x, so the Pro V1x is what you must use on every stroke. If the "one ball rule" is not in effect, however, golfers may swap out different types of golf balls at any point in a round of golf, so long as the change is made in-between holes rather than during the play of a hole. Rule 15-1 states: "A player must hole out with the ball played from the teeing ground ..." The One Ball Condition Says in the Rule book Here is the most relevant text from the rule book about the one-ball rule, which appears in Appendix I, Part B-2(c): One Ball Condition If it is desired to prohibit changing brands and models of golf balls during a stipulated round, the following condition is recommended: "Limitation on Balls Used During Round: (Note to Rule 5-1) (i) "One Ball" Condition During a stipulated round, the balls a player plays must be of the same brand and model as detailed by a single entry on the current List of Conforming Golf Balls. Note: If a ball of a different brand and/or model is dropped or placed it may be lifted, without penalty, and the player must then proceed by dropping or placing a proper ball (Rule 20-6). Penalties and further information can be found in the noted part of Appendix I, available on usga.org or randa.org.