A review of the case histories of ten patients with optic tract lesions, an uncommon clinical entity, showed the primary characteristic to be a homonymous visual field defect that may be complete or incomplete. When the defect is incomplete, there is relative incongruity. When it is complete, there is an associated contralateral relative afferent pupillary defect. Visual acuity and color vision are preserved, unless there is bilateral involvement or anterior extension to involve the optic nerve or chiasm. When of sufficient duration, the contralateral fundus demonstrates band or "bow tie" atrophy of the disc and nerve fiber layer.