A recent report documents three homosexual men with porphyria cutanea tarda associated with acquired immune deficiency syndrome (AIDS). We report two brothers with hemophilia and human immunodeficiency virus (HIV) exposure who developed porphyria cutanea tarda. These brothers are heterosexual, have familial porphyria cutanea tarda, and developed overt familial porphyria cutanea tarda in their early twenties. One brother's symptoms were provoked by attending an ultraviolet A suntanning parlor. Our two patients, unlike the previously reported three patients, have not developed AIDS, though one patient has evidence of defective cell-mediated immunity. Three of the five cases of porphyria cutanea tarda associated with HIV infection involved familial porphyria cutanea tarda. It now may be advisable to order HIV serology tests in patients who have porphyria cutanea tarda. We recommend that HIV-positive individuals avoid ultraviolet A radiation because of its immunosuppressive effects in persons already at risk of immunosuppression. Such exposure is further contraindicated in those individuals with porphyria cutanea tarda.