This is a report of an atypical fibrous histiocytoma in the skull of an infant, who at the age of 3 months was noted to have a "lump" beneath the scalp in the right parietal region. It was about 2 cm in diameter, and the scalp was movable over it. Physical examination was otherwise normal. Radiographs showed erosion of the scalp deep on the palpable mass. At operation a neoplasm was found, which had destroyed the bone and invaded the adjacent temporal muscle and dura mater. The tumor was removed en bloc after the surrounding bone had been excised. Histological examination using light and electron microscopy revealed the tumor to be an atypical fibrous histiocytoma. Radiation therapy was not given. There has been no recurrence for 7 years.