Some persons living with HIV/AIDS (PLWHA) engage in periods of sexual abstinence. Baseline data from a larger study of homeless/unstably housed PLWHA indicated that 20% (125/644) intentionally abstained from sex in the past 90 days. Reasons included: (1) ‘not interested’ (n = 78); (2) did not want to infect someone (n = 46); and (3) did not have a partner (n = 37). Abstinence was less likely among all who had a main partner. Among men who have sex with men (MSM), abstinence was less likely among those with a detectable viral load. It was more likely among heterosexual men who were experiencing current housing problems and who had at least a high school education. Among women, abstinence was less likely among African Americans and those whose social networks were more aware of their HIV status. Better understanding of motivations to abstain may improve how programs serving PLWHA address this issue.