Employing HIV-infected peer counselors in secondary prevention interventions for MSM is appealing for scalable interventions. One-hundred-seventy-six HIV-infected MSM at their primary care facility participated in a secondary HIV-prevention study delivered by HIV-infected MSM peers. Of those who entered the intervention and completed the initial intake, 62% completed all four of the intervention sessions, and 93% completed at least one. While there was no overall change in transmission risk behavior (TRB) for the whole sample, among those who reported HIV TRB at baseline (n = 29), there were significant reductions in TRB over the next year. Themes that emerged in qualitative exit interviews conducted with a subset of participants centered on peer counselor quality, intervention implications, and intervention experience. This demonstration project provides initial evidence for the ability to recruit HIV-infected MSM in care into a peer-based intervention study, and shows how a peer-based intervention can be delivered in the context of HIV care.