The authors report a case in which an enlarging skull fracture was surgically repaired on the fourth day after the initial injury. A 5-month-old boy fell from his father's arms and was hospitalized with a large, irregular protrusion in the left parieto-occipital region and right hemiparesis. Plain skull films showed a diastatic linear fracture with a maximum width of 8 mm, which expanded to 11 mm by the fourth day. Computed tomography (CT) scans revealed a cerebral contusion just beneath the fracture as well as a left subdural effusion. At operation, the contused brain tissue was found to have herniated over the bone defect. Craniotomy revealed a large dural defect, which was repaired with lyophilized dura. The patient was discharged with no neurological deficit. On the basis of a review of 58 recently reported cases of skull fracture, the authors conclude that the following conditions warrant consideration of early surgery: 1) a diastatic skull fracture with a width of at least 4 mm; 2) CT demonstration of a cerebral contusion beneath the fracture; 3) overlying scalp swelling; and 4) a neurological abnormality contralateral to the fracture. Performing surgery before the fracture gap becomes scalloped will result in more rapid neurological recovery and reduce the likelihood of enlargement of the fracture.