OBJECTIVES: Anabolic prohormones, similar to anabolic-androgenic steroids, are sold as dietary supplements in the United States.  There is very little known about the health outcomes associated with exposure to prohormones.  The objective of this study was to assess health outcomes and user perceptions about health outcomes associated with prohormone use. METHODS: A self-administered survey was developed and deployed via two e-forums dedicated to prohormone use.  Questions included information about health outcomes, beliefs about the commonality of side effects in users, and prohormone use characteristics including number of substances taken, number of cycles completed in a year, and taking the recommended or excess dosage. Outcomes were correlated with beliefs.  Logistic regressions were used to measure the association between dose categories and self-reported outcomes.  A multiple risk factor analysis looked at the association between higher than average number of self-reported outcomes and several combined risk indicators.  Combined risk indicators comprised of taking above recommended dose merged in combination with highest number of substances per cycle, highest number of cycles per year and having also taken AAS in the last year, respectively. RESULTS: Eighteen self-reported outcomes were generated from 65 responders.  Users reported an average of 2.49 (SD-0.60) outcomes in their last prohormone cycle.  Correlations showed those who experienced no outcomes believe adverse events are uncommon (R=0.26, P=0.04).  Conversely, those who experienced the highest number of outcomes are not correlated with the belief that outcomes are common (R=0.17.P=0.16). No outcome was significantly associated with taking more than the recommended dose.  Multiple risks showed no significant association with an above average number of reported outcomes CONCLUSIONS: This study is a pilot into an understudied population.  Despite having a small sample, this study is the first of its kind in compiling self-reported outcomes in prohormone users.