Sixty-six untreated patients with advanced non-Hodgkin's lymphoma of favourable histological type were allocated alternately to initial treatment with cyclophosphamide, vincristine, and prednisolone or with chlorambucil. The complete remission rate was higher in the group receiving combination chemotherapy, but the overall response rate was the same for both groups. The mean duration of complete remission was the same as that of good partial remission, and was the same for both treatments. The duration of remission was influenced by histological type and extent of disease at presentation, but not age. Those who responded to the initial treatment (whether with complete or with good partial remission) survived significantly longer than did non-responders. It is concluded that neither treatment is satisfactory and that new treatment programmes are needed for patients with a favourable prognosis, especially young patients with extensive disease.