Of 1360 consecutive patients with Hodgkin's disease treated at Stanford University, 1312 patients (96%) had complete remission, but 424 patients had a relapse. Fifty-five patients had relapses 36 months or more after completion of therapy. The actuarial risk of relapse in patients disease-free 3 years after therapy was 12.9%. The occurrence of late relapse was significantly related to stage I disease and nodular sclerosis histologic subtype. Late relapse was detected in 88% of patients by history, physical findings, or chest radiographs. Most patients with stage III and IV disease had late relapses in previously irradiated nodes or extranodally, but patients with stage I and II disease had late relapses primarily in unirradiated nodes. Disease-free survival after salvage therapy for late relapse was similar to that seen after treatment of earlier relapse. Prolonged surveillance of patients for late relapse is necessary after treatment of patients with Hodgkin's disease.