Objectives. We examined views on rectal microbicides (RMs), a potential HIV prevention option, among men who have sex with men and transgender women in 3 South American cities. Methods. During September 2009 to September 2010, we conducted 10 focus groups and 36 in-depth interviews (n = 140) in Lima and Iquitos, Peru, and Guayaquil, Ecuador, to examine 5 RM domains: knowledge, thoughts and opinions about RM as an HIV prevention tool, use, condoms, and social concerns. We coded emergent themes in recorded and transcribed data sets and extracted representative quotes. We collected sociodemographic information with a self-administered questionnaire. Results. RM issues identified included limited knowledge; concerns regarding plausibility, side effects, and efficacy; impact on condomuse; target users (insertive vs receptive partners); and access concerns. Conclusions. Understanding the sociocultural issues affecting RMs is critical to their uptake and should be addressed prior to product launch.