Twenty-six cases of infantile acute subdural hematoma treated between 1972 and 1983 were reviewed. The series was limited to infants with acute subdural hematoma apparently due to minor head trauma without loss of consciousness, and not associated with cerebral contusion. Twenty-three of the patients were boys, and three were girls, showing a clear male predominance. The patients ranged in age between 3 and 13 months, with an average age of 8.1 months, the majority of patients being between 7 and 10 months old. Most of the patients were brought to the hospital because of generalized tonic convulsion which developed soon after minor head trauma, and all patients had retinal and preretinal hemorrhage. The cases were graded into mild, intermediate, and fulminant types, mainly on the basis of the level of consciousness and motor weakness. Treatment for fulminant cases was emergency craniotomy, and that for mild cases was subdural tapping alone. For intermediate cases, craniotomy or subdural tapping was selected according to the contents of the hematoma. The follow-up results included death in two cases, mild physical retardation in one case, and epilepsy in one case. The remaining 23 patients showed normal development. The relationship between computerized tomography (CT) findings and clinical grading was analyzed. Because some mild and intermediate cases could be missed on CT, the importance of noting the characteristic clinical course and of funduscopic examination is stressed.