Forty three patients with lymphomas or chronic lymphocytic leukemia were treated with intravenous methyl ester of streptonigrin. The total dose for a single course ranged from 0.05 to 0.3 mg/kg, the optimum being 0.1 mg/kg. Thirty patients lived for at least 6 weeks and were considered evaluable. Nine objective remissions were seen in Hodgkin's disease, 5 in lymphocytic lymphoma, 2 in mycosis fungoides and 4 in chronic lymphocytic leukemia. The other 10 patients showed some evidence of favorable drug effect. Immediate toxic reactions were mainly nausea and emesis, though 3 patients had striking but reversible hypotension at the time the drug was administered. Thrombocytopenia occurred in 24 patients and leukopenia in 15 patients. Marrow suppression was generally reversible in 2 to 3 weeks.