From a series of 230 subjects with infantile spasms (I.S.) observed from 1955 to 1982, 191 cases with sufficient data on follow-up and evaluation were selected. The period of follow-up in 100 subjects ranged from 3 months to 3 years and was more than 3 years in the remaining 91 patients. Disappearance of spasms and normal psychomotor development was observed in 34 of the 61 idiopathic and post-infectious cases. In 130 subjects with secondary forms normal psychomotor development was observed in only two patients; disappearance of spasms was noted in 54 and normalisation of the EEG in 13 subjects. Satisfactory long term results can be obtained with a relatively low dose of corticotropin in a considerable number of patients having idiopathic and post-infectious forms of I.S. To obtain the best results treatment should be started as soon as possible.