PURPOSE: The purpose of this study was to evaluate knowledge of the skin protection factor (SPF) rating among various physical activity groups. The SPF factor is commonly used in labeling for sunscreens and, now, for clothing. METHODS: A total of 1208 submitted answers to a demographic and 10 question T/F survey. Each participant listed activities in which they participate. Surveys were distributed during regional health fairs, skin cancer screenings, medical school classes, and dermatology and surgical oncology patient visits. Knowledge of SPF was measured by the true/false survey statement: "SPF (sun protection factor) represents the number of minutes a person can be out in the sun with sunscreen on and be getting the same amount of UV rays as if they were out in the sun with no sunscreen on for one minute." RESULTS: In the groups listed, the above true statement was the most or 2nd to most incorrectly answered. In this survey, all ten statements are true for the purpose of being an educational tool. Participants may have been able to discern the answer pattern. Because of this, the percentage of correct answers to the SPF question is probably skewed high. In a future study, we plan to administer a revised survey instrument with a mix of true and false statements to specific sports teams.Table: No caption providedCONCLUSION: Even though "SPF" is a commonly used acronym indicating the level of sun protection offered in sunscreen and clothing, many people do not understand what SPF actually means. With ACSM and AHA guidelines and their support of the US Dept of Health and Human Services (DHHS) physical activity guidelines, we recommend that the ACSM address skin cancer prevention education, and, in particular, the promotion of accurate understanding of SPF nomenclature.