Positive choices (PC), a brief sexual risk reduction intervention conducted with newly HIV-diagnosed men who have sex with men (MSM), was evaluated for preliminary efficacy. Participants were enrolled if they reported unprotected anal intercourse (UAI) in the three months prior to HIV diagnosis (n = 102). Three months after diagnosis, participants completed baseline assessments and were randomly assigned to receive the 3-session PC intervention or the comprehensive standard of care (C-SoC) at a community health center. Participants completed assessments at 3- (post intervention), 6-, and 9- months after baseline. Compared to C-SoC participants, PC participants significantly reduced the frequency of UAI with HIV serodiscordant (HIV negative or status unknown) partners over the 9-month follow-up period. No differences by condition were found in the frequency of UAI with all partners. The findings from this trial suggest that brief risk reduction approaches for newly-diagnosed MSM integrated into HIV care can benefit secondary HIV prevention efforts.