HIV/AIDS is an extremely important public health challenge. Bipolar disorder spectrum has a significant prevalence, reported to be around 2.6%. This study analyses the relationship between sexual behaviors among MDQ positive and MDQ negative patients and its influence in HIV infection, and the impact of HIV diagnosis in both groups. Two hundred outpatients from a specialized clinic for HIV-care located in Walter Cantídio's University Hospital in Fortaleza, Brazil answered to a demographic questionnaire, the Mood Disorder Questionnaire (MDQ) and a sexual behavior questionnaire based on WHO's Behavioral Surveillance Surveys (BSS). Fifteen percent (N=30) of all HIV positive patients were MDQ+. The MDQ+ group was more likely to: be or have been married, have offspring, have sex with commercial and non-regular partners, have infrequent condom use with non-regular partners and of not have used condom in their first sex. Despite more sexual practices among MDQ+ patients before HIV diagnosis, these patients had a more significant reduction of all behaviors after HIV diagnosis than the MDQ- group.