One hundred sixty-one patients with advanced Hodgkin's disease achieved complete remission after combination chemotherapy. Of these, 52 (32%) have subsequently relapsed and the patterns of relapse have been studied. The probability of relapse increases with increasing stage and particularly with the presence of systemic symptoms. Patients with Nodular Sclerosis histology are more likely to relapse than those with other histologies. Patients relapse primarily (92%) in sites of previous disease and particularly in nodal sites (75%). Nodal sites most frequently involved at relapse are the central nodal areas and the left supraclavicular area. When patients relapse in new sites they tend to be either adjacent to sites of previous disease which relapse or to be contiguous with previously involved sites of disease. In the small number of patients who received prophylactic radiation therapy to sites of nodal disease after complete remission, the pattern of relapse was not significantly altered.