Abstract This study assesses the prevalence of bipolar disorder (BD) among 196 HIV-infected adult outpatients attending in a specialized unit in Fortaleza, Brazil. Patients were interviewed with the Mood Disorder Questionnaire (MDQ), the Mini International Neuropsychiatric Interview (MINI), the Alcohol Use Disorders Identification Test (AUDIT), and a socio-demographic questionnaire based on WHO's behavioral surveillance surveys. Positive MDQ screening was found in 13.2% (N=26) and the BD diagnosis was confirmed in 8.1% (N=16) of the sample. There is an almost four times higher prevalence of BD among the HIV-infected patients of the sample (8.1%) than in the general population from the USA (2.1%). The prevalence of BD type I in the HIV patients was 5.6% (N=11) which is almost six times higher than the US general population (1%). The odds ratios of sexual behaviors and substance abuse variables correlated with BD were calculated. The variables associated with the diagnoses of BD were sex with commercial partners, sex outside the primary relationship, alcohol use disorders, and illicit drug abuse. The most common psychiatric comorbidity in the BD group was substance abuse (61.5%). A better understanding of psychiatric comorbidities and behavioral aspects of HIV-positive patients may help in improving long-term outcome of these patients.