Abstract Objectives: To determine the safety of the candidate vaginal microbicide SPL7013 gel (VivaGel) when applied to the penis. Methods: A randomized, double-blind, placebo-controlled study. Thirty-six healthy men (18 circumcised, 18 uncircumcised) were randomized in a 2:1 ratio and treated with 3 SPL7013 gel (n = 24) or placebo gel (n = 12), applied once daily for 7 days. Genital toxicity was determined by interview, diary, and examination. Results: There were 10 genital adverse events (AEs) in 6 men (25 ) receiving SPL7013 gel and 5 genital AEs in 4 men (33 ) receiving the placebo that were possibly or probably related to the study product (difference of -8 , 95 confidence interval: -40 to 23 , P = 0.70). The most common genital AEs were genital pruritus and application site erythema. All genital AEs were mild (grade 1), and all but 1 in the placebo group were transient. Analysis of vital signs, nongenital AEs, and laboratory results indicated no safety or tolerability issues with SPL7013 gel, irrespective of circumcision status. There was no detectable absorption of SPL7013 into the plasma. Conclusions: Three percent SPL7013 gel was safe and well tolerated, and comparable with placebo, when administered to the penis of both circumcised and uncircumcised men once daily for 7 days, with no evidence of systemic absorption or toxicity. Copyright ? 2009 by Lippincott Williams Wilkins.