From July 1983 to December 1989, 31 previously untreated patients with non-Hodgkin's lymphoma were treated with modified CHOP regimen (cyclophosphamide 300 mg/m2 on day 1, aclacinomycin 40 mg/m2 on day 1, vincristine 0.7 mg/m2 on day 1 and prednisolone 40 mg/m2 on days 1-5). The therapy was repeated at 2-week intervals. The complete response rate was 66.7% for clinical stage (CS) II according to the Ann Arbor criteria, 60.0% for CS III and 33.3% for CS IV, respectively. The 5-year survival rate was 100% for CS II, 36.6% for CS III and 34.6% for CS IV, respectively. Clinical effects of modified CHOP regimen were almost the same as those of other therapies including adriamycin from the standpoint of 5-year survival rate. On the other hand, the myelosuppression accompanying modified CHOP therapy was not severe. Only one patient had a white blood count below 1,000/microliters during 6 courses of the therapy. It is thought that this regimen is useful to enhance the quality of life of patients because of no severe complications such as myelosuppression.