Therapeutic progress has much improved the prognosis of Hodgkin's disease; therefore long-term complications of the treatment have become a major problem. Among these, the authors focused on osteonecrosis of the femoral head, and conducted a retrospective study on 182 patients treated with inverted-Y-field radiation therapy combined to MOPP chemotherapy in 129 cases. Femoral osteonecrosis was found in 6 patients (3.3%), 5 males and 1 female; 4 of them received combined modality treatment (inverted-Y radiation therapy + MOPP), and 2 radiation therapy alone. The interval between the end of treatment and the radiological finding of femoral osteonecrosis ranged from 23 to 54 months, with a mean of 35 months. On the whole, 10 cases of osteonecrosis of the femoral head (4 bilateral, and 2 unilateral) were observed, and 4 fractures involving the anatomic neck. According to our results, neither a safety dose-limit nor an optimal schedule of combination therapy could be fixed. Besides radiological features and the problems of differential diagnosis, the authors considered the pathogenesis of femoral head osteonecrosis in the patients with Hodgkin's disease treated with radiotherapy alone or combined to chemotherapy, and suggested the existence of a personal proneness to the lesion and the role of ionizing radiations, corticosteroids and cytotoxic agents, as inducing factors. Because of the different and unexpected reaction of each patient to the treatment, osteonecrosis prevention is very difficult: however, its complication may be reduced--or even avoided--by subjecting the treated patients to periodic clinical and radiological examinations.