An epidemiological inquiry has been done in France after the notification in the USA and England of four cases of Creutzfeldt-Jakob disease in patients previously treated with hGH. Between 1959, when hGH treatment in France was started, and August 1985, the date the survey began, 1698 patients were registered for treatment. Current information (less than three months old) was obtained for 1620 patients (95.4%). Death was reported in 31 patients, but none could be related to Creutzfeldt-Jakob or similar disease. Pathological events were observed in 213 living patients (13.1%). Among them, four were diseases classified as possibly related to a viral infection. The first case had acute lymphoid leukaemia; the second case had polyradiculoneuritis associated with hepatitis. In both cases the disease resolved completely. Two other patients had acute encephalitis which started less than two years after the onset of treatment and which resolved spontaneously. Even though the acute evolution and the spontaneous clinical recovery are not consistent with Creutzfeldt-Jakob disease, a relationship with hGH therapy could not be completely excluded. Finally, five treated children had later malignancies which raises the question of the long-term secondary effects of hGH upon cellular proliferation.