A 54-year-old woman with leucocytosis and skin lesion was hospitalized and diagnosed as chronic type adult T cell leukemia (ATL) in August 1989. Since her ATL cell count and LDH level increased after hospitalization, oral administration of etoposide was started at a dose of 100 mg/day for seven days. The oral administration of etoposide induced another chronic state of ATL. After 10 months without medication, she was readmitted because of an acute ATL crisis. After daily administration of etoposide at a dose of 50 mg/day, the white blood cell count and serum LDH level decreased to the normal range, and abnormal lymphocytes of peripheral blood disappeared. The low-dose daily administration of etoposide at a dose of 25 approximately 50 mg/day could be maintained over six months. No severe side effects except for alopecia and mild myelosuppression were noted during the treatment. Chronic daily administration of oral etoposide is one candidate for the treatment of ATL in an outpatient clinic.