This study estimated the prevalence, and identified the correlates, of HIV, chlamydia, syphilis, and Hepatitis B among patients seeking treatment for a mental disorder in India. Patients (n = 948) submitted a blood sample for serologic testing and participated in a brief interview. Lifetime prevalence rates were nearly 2% for HIV, 10% for chlamydia, 3% for Hepatitis B, and 3% for syphilis; 15% of patients had evidence of at least one infection. Bivariate associations between infection status and patient characteristics, including age, gender, psychiatric diagnosis, did not reveal any consistent risk profile. Instead, behavioral characteristics (i.e., multiple partners, exchanging sex for money, and engagement in anal sex) were associated with infection status. Recommendations for the sexual health care of psychiatric patients in India are provided.