A 66-year-old woman with malignant histiocytosis was treated with a combination of recombinant gamma interferon (GI-3) and etoposide. Following partial response to intravenous gamma interferon (9 x 10(6) units (U)/day) alone, the patient received an eight-months course of subcutaneous gamma interferon (0.5 x 10(6) U/day) and intravenous etoposide (100 mg/week). After two years, the patient remains in complete remission. The present case report discusses the successful use of combination gamma interferon and etoposide for the treatment of malignant histiocytosis.