A number of malignancies which have been seen with other immunodeficiency diseases have appeared in patients immunosuppressed by the human immunodeficiency virus (HIV) infection. These include Kaposi's sarcoma, lymphomas, superficially spreading basal cell carcinomas, and squamous cell carcinomas. The fact that Kaposi's sarcoma is the most common of these malignancies and is seen almost exclusively among homosexual men remains an enigma. The dermatological treatment of Kaposi's sarcoma includes observation, surgical excision, radiation therapy, interlesional chemotherapy, and topical liquid nitrogen. When the disease becomes more aggressive, systemic chemotherapy, using a combination of chemotherapeutic agents, will often slow disease progression. It is essential that the chemotherapy be given in a dose that will slow the course of the malignancy, but will not further immunosuppress the patient. The treatment of lymphomas in HIV-infected patients has been less than satisfactory, with a high mortality rate. Aggressive therapy of these lymphomas using combination therapy has been the most successful in increasing survival.