Three patients developed non-Hodgkin's lymphoma (NHL) 3-6 years after treatment for Hodgkin's disease (HD). In no instance was there evidence of recurrence of HD following the initial chemotherapy or radiotherapy. None of these patients had received both radiation therapy and chemotherapy. The histologic classification of the developing of the developing NHL for the three patients was (1) diffuse, poorly differentiated lymphocytic, (2) nodular histocytic, and (3) nodular, poorly differentiated lymphocytic. In no instance was there any histologic similarity to the original HD. Perhaps most important with respect to histology was the easily demonstrable presence of Reed-Sternberg cells at the time of original diagnosis and their absence with onset of NHL. All patients responded well to conventional chemotherapy for NHL and are alive at 23+, 37+, and 65+ months after that secondary diagnosis. This report, when coupled with at least ten other such reported patients, suggests that NHL may be a relatively uncommon but significant complication of therapy for HD and must be distinguished for recurrence of HD.