The long-term results achieved with CHOP chemotherapy in 131 patients with non-Hodgkin's lymphoma of diffuse histological pattern and in advanced stages were analysed. The mean age of the patients was 49 years. Complete remission was achieved in 68 cases (60 %). There was good tolerance in general terms, without any lethal complications. The median survival was 27 months; 28 patients (25 % of the whole series) are alive and disease-free after 10 years, so they can be considered as cured. High lactate-dehydrogenase levels, bulky tumoural mass and high degree of histological malignancy were identified as poor-prognosis factors. CHOP chemotherapy appears as a useful means of treating non-Hodgkin's lymphoma, as shown by the number of patients achieving long lasting remission and by the tolerance. Nevertheless, this treatment is of less value in patients with poorer prognosis, in whom other regimens must be borne in mind.