This study investigated whether homeless men are a bridge group for transmission of HIV to the general population in India. A cross-sectional study design was used to measure subjects' past and current sexual activities. We surveyed 493 of 606 homeless men aged 18-49 years who live in public places in Kolkata, India, who were invited to take part in a structured interview, using a CD player and earphones. Almost two-thirds of respondents had never attended school. Sex with commercial sex worker (CSWs), multiple sex partners, and inconsistent condom use were common. About 90% of married homeless men visited CSWs, but only 3.3% consistently used condoms. AIDS awareness and risk perception were very low. Less education and being married but not currently living with wife were associated with high-risk sexual behaviors. Homeless men should be considered a potential bridge for HIV transmission from CSWs to the general population. Appropriate non-written communication strategies targeted to homeless people are urgently needed. Community intervention programs targeting the homeless, such as the 'Popular Opinion Leader' model, should be designed and evaluated.