Nine cases of fibroblastic lesions occurring in the cranium of young children were reviewed. The age of the patients at the time of initial treatment ranged from three weeks to six years (median 18 months), with the lesions being congenital in two cases. There was 2:1 male predominance. The size of the lesions averaged 2.5 cm in greatest dimension with the largest being 9.0 cm. All cases presented as rapidly growing masses with a preoperative duration of only two months. The lesions presented as soft-tissue masses deep in the scalp with involvement of the underlying cranium in all eight of the cases in which roentgenograms or operative reports were available for review. Characteristically, there was erosion of only the outer table of the skull, although in three cases the lesion extended through the inner table to attach to the underlying dura mater. It was not possible to detect the exact site or origin, although origin from one of the deep fascial layers of the scalp or the underlying periosteum seems most likely. Microscopically, the lesion appeared to be a proliferation of loosely arranged fibroblasts which most closely resembled nodular fasciitis. Mitotic figures as well as foci of osseous metaplasia were present. Treatment consisted of excision of the mass with local resection or curettage of the affected underlying bone in some cases. Followup revealed a benign clinical course with no recurrent or aggressive behavior.