A phase II study of new anthracycline, THP, was conducted in 46 patients with hematological malignancies in a cooperative study. THP was given intravenously either at a dose of 13-34 mg/m2 for 3-5 consecutive days or 35-50 mg/m2 at 3-4 week intervals. Of 21 patients with acute leukemia, complete response (CR) was observed in 3 patients and partial response (PR) in 4. Of 22 patients with malignant lymphoma, CR was observed in 2 and PR in 6. The predominant toxicity was myelosuppression. Leukopenia was noted in 73% of patients and thrombocytopenia in 14%. Anorexia, nausea and vomiting were observed in 49%, 26% and 23%, respectively. Alopecia and acute cardiac toxicities were mild and recovered quickly on discontinuation of THP. Thus, THP was found to be effective for acute leukemia and malignant lymphoma.