Thirty-eight cases of optic gliomas seen at the University of California, San Francisco, were reviewed. Two patients died in the postoperative period and were excluded from the follow-up analysis. Twenty-nine cases (76%) involved the optic chiasm, nine (24%) cases were confined to one optic nerve. Most tumors were slow growing and progressive although there were three cases of adult chiasmal gliomas which exhibited unusually aggressive behavior. The three cases are presented in detail. After a mean follow-up period of 9.4 years, the 10-year overall actuarial survival was 87%. Relapse-free survival was 55% at 10 years. Chiasmal tumors had a poorer prognosis compared to optic nerve tumors with 56% of chiasmal tumors recurring versus 22% of optic nerve tumors. Radiotherapy was beneficial in chiasmal gliomas, initially improving vision in 35% (6/17) and decreasing recurrence from 86% (6/7) without radiation therapy to 45% (9/20) with radiation therapy. Optic gliomas are not benign, self-limiting lesions, and therefore require treatment. Radiotherapy is effective in chiasmal gliomas and should be used early in the management of these tumors. No advantage to radiotherapy could be demonstrated for optic nerve gliomas, although the number of these cases analyzed was small.