We report on 4 boys (3 in one family) who have a remarkably constant syndrome of childhood-onset choreoathetosis with later spasticity, postnatal microcephaly, growth and mental retardation, apparent external ophthalmoplegia and varying degrees of deafness. The pedigrees are consistent with X-linked inheritance. The syndrome is compared and contrasted with others comprising basal ganglion dysfunction in childhood. It is concluded that clinically and genetically the condition is unique.