Problem: Risky sexual behaviors are common among college undergraduate students, and previous experience of interpersonal potentially traumatic events further increase the risk to engage in these behaviors. Little is known about how physical activity level and organized sports participation moderate the relationship between interpersonal potentially traumatic events and risky sexual behaviors. Methods: Multiple regression analyses were conducted to examine relationships between interpersonal potentially traumatic events, physical activity, and risky sexual behaviors among undergraduate students. Results: Organized sports participation exacerbated the association between interpersonal potentially traumatic events and risky sexual behaviors for males but attenuated the association for females. However, no moderating effect was found for physical activity level. Conclusions: Organized sports participation served as a significant moderator on the association between interpersonal potentially traumatic events and risky sexual behaviors that warrants further investigation.