Background: Treatments using UV, UVB, or oral psoralen and UVA (PUVA) have been advocated for the care of HIV-infected persons with skin diseases. Concerns about the safety of these treatments exist. Objective: We attempted to determine the characteristics of HIV infected persons receiving UV therapy and establish the reasons for and type of treatment administered. Methods: During two 2-week periods, we prospectively ascertained basic information on all patients treated at 40 phototherapy clinics and detailed clinical information on patients known to be infected with HIV. Results: We identified 3716 persons receiving UV therapy, including 311 known to be infected with HIV. When compared with patients not known to be infected with HIV, HIV-positive patients were significantly more likely to be treated with UVB rather than PUVA and were more likely to be treated for pruritic conditions rather than psoriasis. Conclusion: There were great variations in the relative reliance on UVB and PUVA among centers. There appears to be no agreement as to which type of UV therapy is optimal for patients infected with HIV. Most patients known to the treating clinician to be HIV positive are in the advanced stages of HIV disease. The number of persons with less advanced HIV disease receiving treatment remains unquantified but may be even more clinically important. (J Am Acad Dermatol 1998;39:48-55.)