A 23 year-old female had a giant cell tumor originating in the right temporal bone. A diagnosis was maed by biopsy. Microscopically it was sarcomatous in part. Two courses of radiation therapy, each total dose being 6000 rads and 3000 rads in air, were employed with good subjective response for a short duration. However, the tumor involving the petrous bone and the mastoid process extended, invading the epipharynx and the clivus. The patient died one year after onset.