The relapse rates of patients with malignant lymphoma have been analyzed in relation to the number of patients in complete remission (CR) at yearly intervals after the onset of therapy. Several different patterns of relapse have been identified. Patients in CR from nodular poorly differentiated lymphocytic lymphoma have a low rate of recurrent disease (14%) during the first year of treatment but rates of relapse in succeeding years have not decreased. Patients with diffuse poorly differentiated lymphocytic lymphoma have a significantly higher relapse rate during the first year of treatment (33%). However, remission duration curves suggest that the risk of relapse is decreasing with time. Patients with diffuse histiocytic lymphoma, who initially have the greatest risk of disease recurrence (42%), subsequently showed a significant fall in their rate of relapse. As many as 50% of these patients who attain a CR may have been cured of their disease. An analysis of CR duration curves may be used to determine the effective doubling time of various malignant diseases and to estimate cure rates within a few years after the onset of therapy.