Congenital fibrosis of the extraocular muscles (CFEOM) is a strabismus syndrome characterized by non-progressive, restrictive ophthalmoplegia of the extraocular muscles and congenital blepharoptosis. Three clinical phenotypes for familial CFEOM (CFEOM1, 2, and 3) have been delineated, for which two genes have been identified to date: KIF21A for CFEOM1 and 3 and PHOX2A/ARIX for CFEOM2. Insights gained from molecular genetics have strengthened the hypothesis that CFEOM results from the dysinnervation of the extraocular muscles supplied by the oculomotor and/or trochlear nerves. Continued study of this syndrome should help to further elucidate the pathogenesis of eye movement disorders.