Previous research found up to 14% of men who go to bathhouses engage in unprotected anal intercourse (UAI) and tend to have multiple sexual partners during their bathhouse visit, thus appearing to support concerns that such venues could foster acute outbreaks of new HIV infections. We conducted a two-stage probability sample of men exiting a gay bathhouse, and focused our analysis on whether the partnering patterns of the men who engaged in UAI present such a risk. Among patrons who had oral or anal sex during their visit (n = 758), 16.7% were HIV+, and 13.9% engaged in UAI. Although men had multiple sex partners during a visit, they had UAI with only one of those partners, on average, and withdrawal prior to ejaculation occurred in the vast majority of UAI incidences. Thus, the risk of sexual transmission of HIV during the bathhouse visit was typically within isolated dyads rather than patterns of multiple sexual encounters that might put many men at risk during a single visit, and men who did engage in UAI tended to withdraw prior to ejaculation, potentially mitigating the risk of HIV transmission.