Introduction: For health and ethical reasons, collegiate sport administrators are interested in managing athletes' attitudes towards performance enhancing drugs (PEDs). Research has called for a better understanding of the psychosocial processes through which permissive attitudes towards PEDs are formed. This study explored the potential influence of male and female competitive collegiate athletes' harmonious passion on their attitudes towards PEDs. Method: A survey was administered to varsity and competitive recreation athletes (n = 587) participating in one of seven team sports at four Canadian universities. Participants completed the performance enhancement attitudes scale (Petróczi, 2006: PEAS), the harmonious passion subscale from the passion scale (Vallerand et al., 2003) and a brief demographic questionnaire. Data were analyzed using Hayes' (2013) PROCESS macro in SPSS to examine the potential moderating role of sex in the association between harmonious passion and attitudes towards PEDs. Results: Males reported more lenient attitudes towards PEDs. No sex difference for harmonious passion was reported. The influence of passion on attitudes towards PEDs is moderated by sex, such that harmonious passion is negatively associated with males' attitudes toward PEDs, but unrelated for females. Discussion: This study demonstrates that for male competitive athletes, harmonious passion plays a significant role in decreasing the development of attitudes towards PEDs. These results may help administrators to target efforts for decreasing permissive attitudes towards PEDs through the construct of passion, specifically harmonious passion. Promoting the harmonious aspects of competitive sport and physical activity may be effective at challenging males' liberal attitudes towards PEDs.