Innovative, low-cost, and acceptable measures are needed to reduce sexually transmitted infections (STIs) including HIV. Use of a topical microbicide wipe for penile cleaning before and after sex might be effective in preventing STIs. However, evaluation of this simple method has not been done. Two studies were conducted in Malawi to determine the safety, acceptability, and potential efficacy of a benzalkonium chloride topical penile microbicide wipe. The first study was a phase 1 dose-escalating clinical trial among low-risk circumcised or uncircumcised HIV-negative men. The second study was a pilot before-after efficacy study among uncircumcised HIV-negative or -positive men. In the first study 24 circumcised and 27 uncircumcised men were enrolled. During the entire study period, 18 adverse events (AEs) were reported, and 3 AEs were confirmed by physical examination. Acceptability concerns did not increase with dose escalation, and adherence to use of the wipe ranged from 89%-95%. In the second study, 27 men were enrolled. Gram stain and culture tests showed significant reductions in frequency of several organisms after use of the wipe, including STI-associated bacteria. This penile wipe is safe, acceptable, and can decrease the frequency of penile colonization with microorganisms. The clinical relevance remains to be determined in larger clinical trials.