Bathhouses and sex clubs were identified as primary venues for HIV transmission during the original HIV epidemic. Because HIV incidence is increasing in some high-risk groups, their potential role in HIV transmission is being examined again. We present an extension of the Bernoulli process model of HIV transmission to incorporate subpopulations with different behaviors in sex acts, condom use, and choice of partners in a single period of time. With this model, we study the role that bathhouses and sex clubs play in HIV transmission using data from the 1997 Urban Men's Health Study. If sexual activity remains the same, we find that bathhouse closures would likely lead to a small increase in HIV transmission in the period examined by this study, although this impact is less than that which would be achieved through a 1% change in current condom use rates. If, conversely, bathhouse closure leads to a reduction of the sexual activity that was in the bathhouse by at least 2%, HIV transmission would be lowered.