Research suggests gender differences in interpersonal relationship factors important to health. This study examined relationship factors associated with HAART adherence among men. The sample (n = 154) comprised 95% African Americans and 48% current illicit drug users; 83% reported HAART adherence. Results revealed adherence was associated with comfort level taking HAART in the presence of close friends, and the interaction between informal care (having someone to care for oneself when sick in bed) and reciprocity of support. Among those with informal care, higher reciprocity of support to caregivers was associated with greater adherence. Promoting men's reciprocity of support to their caregivers and enhancing peer norms of medication taking are important strategies for improving men's adherence. The findings complement previous findings on relationship factors adversely associated with women's adherence. Results suggest the merit of interventions targeting men and their informal caregivers, particularly main partners, and gender-specific, contextually tailored strategies to promote HAART adherence.