128 cases of ATL (adult T-cell leukemia/lymphoma) were divided into 3 subgroups, 70 cases of acute type, 19 cases of chronic type and 39 cases of lymphoma type, and their prognosis were evaluated. Median survival time from the onset of acute type using Kaplan-Meier method was 8 months, that of lymphoma type was 14 months and that of chronic type was 50 months. Median survival time from the start of treatment of acute type was 5 months, that of lymphoma type was 11 months and that of chronic type was 22 months. Relatively short median survival time of chronic type may be due to they had some duration with observation only at first. No significant elongation of survival time could be obtained when acute type was divided into 2 stages, before and after 1982. Twelve patients with non-Hodgkins' lymphoma unresponsive to the first line combination chemotherapy were treated with combination therapy with cis-dichlorodiammineplatinum (CDDP). Ten patients were evaluable for response (4 cases of CR, 6 cases of PR). To stop the HTLV-1 carrier mothers milk for giving their children seems to be effective method to decrease the occurrence of ATL in future.