We describe six patients from five families, who have a syndrome that, to our knowledge, has not been previously reported. The syndrome is characterized by growth failure, ophthalmoplegia, optic atrophy, choreoathetosis, areflexia, hypotonia, dysmorphic facies, and severe mental and motor retardation. Some of the children also had microcephaly and seizures. The clinical course is remarkably uniform and slowly progressive. The abnormalities first noted are delayed psychomotor development and poor weight gain, and the others all develop within the first three years of life. The syndrome seems to be hereditary. Extensive laboratory investigation has not yielded an etiology. Until pathologic material is available, the disorder remains a syndrome and the diagnosis is established by the unique combination of neurological abnormalities.