The skin is commonly affected in the course of human immunodeficiency virus (HIV) infection. In many cases, skin findings may be the earliest sign of HIV disease or acquired immunodeficiency syndrome. When cutaneous diseases occur in unusual settings, such as zoster in a young individual, are increased in severity or fail to respond to routine therapy, the possibility of underlying immunodeficiency should be suspected. Skin diseases in HIV-infected hosts include primary infections, such as those caused by herpes simplex virus and molluscum contagiosum, as well as secondary involvement of systemic diseases, such as cryptococcosis and histoplasmosis. Noninfectious inflammatory processes, such as seborrheic dermatitis and psoriasis, as well as neoplasms, such as Kaposi's sarcoma and basal cell carcinoma, may all be seen in these patients. We review a number of these diseases and discuss their treatment. Clinicians must be aware of the cutaneous manifestations of HIV infection so that the disease will be recognized at an earlier point in time and therapy with zidovudine and prophylactic antibiotics will be instituted where appropriate. ( Arch Intern Med . 1991;151:1295-1303)