Of 11 patients (eight women and three men, ranging in age from 16 to 48 years) who had sarcoidosis of the optic nerve that caused decreased visual acuity and visual field abnormalities, only two were known to have sarcoidosis at the time the visual impairment developed. Four patients had granulomas involving the optic nerve head, four had granulomatous inflammation of the orbital or intracranial optic nerve or chiasm, and three had retrobulbar neuritis. All 11 patients had histologically confirmed idiopathic noncaseating granulomatous inflammation and eight of the 11 had abnormalities compatible with sarcoidosis in chest roentgenograms. In the three patients in whom the serum level of angiotensin-converting enzyme was determined, it was increased in one and normal in the other two. Computed tomography of the anterior visual pathways was the single most useful neurodiagnostic study. Treatment with corticosteroids was beneficial in six of the 11 cases. These cases demonstrated that sarcoidosis should be included in the differential diagnosis of any inflammatory or compressive lesion involving the anterior visual pathways.