The results of treatment of 198 patients with MOPP (mechlorethamine, vincristine, procarbazine, and prednisone) for Hodgkin's disease were analyzed after a median of 14 years of follow-up. Throughout the period of follow-up, 103 patients have remained continuously free of disease. Review of biopsy specimens of 43 patients originally classified as Hodgkin's disease, lymphocyte-depleted type, revealed that ten of these patients actually had diffuse immunoblastic or large cell non-Hodgkin's lymphomas. Of the 188 patients with Hodgkin's disease, 157 achieved a complete response (CR) (84%), and 66% of them (101 patients) have remained disease-free more than 10 years from the end of treatment. Absence of B symptoms and receiving higher doses of vincristine were factors associated with a higher CR rate and longer survival. Patients entering complete remission in five cycles or less had significantly longer remissions than those requiring six or more cycles. Forty-eight percent of the Hodgkin's disease patients have survived between 9 and 21 years (median, 14 years) from the end of treatment. Nineteen percent of the CRs have died of intercurrent illnesses, free of Hodgkin's disease.