Septo-optic-pituitary dysplasia is a syndrome characterized by abnormalities of midline brain structures, optic nerve hypoplasia, and congenital hypothalamic-pituitary insufficiency. Four infants, diagnosed as having clinical variations of this disorder, are described. The first had agenesis of the septum pellucidum and corpus callosum, partial hypothalamic insufficiency, and normal optic nerves. The second had a structurally normal brain, bilateral optic nerve hypoplasia, and panhypopituitarism. The third had bilateral agenesis of the cerebral cortex, bilateral optic nerve hypoplasia and partial hypothalamic insufficiency. The fourth had a structurally normal brain, unilateral optic nerve hypoplasia and panhypopituitarism. A review of the recent literature revealed 191 patients with bilateral optic nerve hypoplasia who were examined for possible existence of this syndrome. Of the 178 patients who had radiographic imaging of the brain, 60% were found to have structural abnormalities. Of the 145 patients evaluated for pituitary function, 62% had evidence of insufficiency. Approximately 30% of fully evaluated patients had evidence of all three components of the syndrome. Because of high incidence of structural abnormalities of the brain and congenital hypopituitarism in patients with optic nerve hypoplasia, we conclude that full evaluation is indicated in patients with any of the three components of the syndrome.