This cross-sectional study evaluated the use and safety of appearance- and performance-enhancing supplements among gay, bisexual, and other MSM (gbMSM) receiving PrEP services in Toronto.  Adult participants on FTC/TDF completed a survey querying reasons for supplement use, type (e.g., muscle-building supplements, anabolic androgenic steroids, fat-burning products), frequency, cost, and factors which would impact the decision to discontinue supplements.  Participants were then included in a retrospective chart review comparing lab abnormalities among people who had never been exposed to these supplements vs. participants who used supplements at least weekly within 6 months.  Analyses included data on 50 participants (median 4.4yrs on PrEP, and 76% reported alcohol consumption).  52% reported supplement use within 6 months; median number of products used per person was 1.5.  The most commonly used products included whey protein (84.6%), creatine supplements (34.6%) and anabolic steroids (23.1%).  35% of participants indicated they would stop product use if they experienced mild side effects and 12% would stop only if they experienced major side effects.  12% of current product users had elevated serum creatinine (stage 1) vs. 0% in the non-use group.  8% of current product users experienced grade 3-4 ALT/AST elevations vs. 0% in the non-use group.  Among supplement users who experienced ALT/AST elevations, most continued their products while others discontinued only a portion.  No participants discontinued all products.