Thirty-two patients with Hodgkin's disease who relapsed after a first complete remission induced by nitrogen mustard, vincristine, procarbazine, and prednisone (MOPP) were retreated with MOPP chemotherapy. Nineteen patients achieved a second complete remission. Median duration of the second complete remission was 21 months. The likelihood of achieving a second complete response could be predicted by the duration of the first response. Fourteen of 15 patients whose first complete remission was longer than 12 months achieved a second complete response in contrast to five of 17 patients whose initial complete remission lasted less than 12 months (P < 0.001). Median survival of all patients in this study who were re-treated with MOPP was longer than 4 years after their first relapse. We conclude that patients with Hodgkin's disease who relapse after a first complete remission induced by MOPP are not necessarily resistant to further MOPP therapy and can achieve long-term survival with MOPP reinduction.