A family with Moebius syndrome is presented. Neurological lesions in the affected members are various: complete VI and VII cranial nerves palsy associated with mental retardation in the proband; left convergent strabismus and mental retardation in a brother of the proband and only mental retardation in a sister of the proband. The brainstem auditory evoked potentials (B.A.E.P.), investigated in the proband and his affected sister, are abnormal. The presence of the anomaly after the 3rd wave is consistent with a disfunction of the auditory tract at a supranuclear level. The mental deficiency and the supranuclear site of the acoustic lesion are an indication for a more general involvement of C.N.S. than cranial nerve nuclei alone. Karyotype and dermatoglyphics of the three affected subjects were normal. The authors hypothesized the same disorganogenetic factor acting very early (4th-6th week of gestational age) on the metamerization process of limb buds mesoderm and brainstem gray matter.