Social media technologies have become increasingly useful tools for research-based interventions. However, participants and social media users have expressed ethical concerns with these studies, such as risks and benefits of participation, as well as privacy, confidentiality, and informed consent issues. This study was designed to follow up with and assess experiences and perceptions of ethics-related issues among a sample of 211 men who have sex with men who participated in the Harnessing Online Peer Education (HOPE) Peru study, a randomized controlled HIV prevention intervention conducted in Peru. We found that after adjusting for age, highest educational attainment, race, sexual orientation, and prior HIV research experience, participants in the intervention group were more likely than those in the control group to have safe sex (p = 0.0051) and get tested for HIV regularly (p = 0.0051). As a result of their participation, those in the intervention group benefited more positively than participants in the control group in improving HIV care (p = 0.0077) and learning where to receive sexual health services (p = 0.0021). Participants in the intervention group expressed higher levels of comfort than those in the control group in joining and seeing other people in the Facebook group (p = 0.039), seeing other people's posts (p = 0.038) and having other group members talk to them online (p = 0.040). We discuss the implications of these results as they relate to social media-based HIV research.