The occurrence of a congenital neurological disorder "spinal dysmyelination" in cross-bred calves in Denmark is reported. A total of 36 affected calves of the Red Danish Dairy breed X American Brown Swiss were detected. The calves occurred in a clear familiar pattern consistent with an autosomal recessively inherited trait, and the parents could be traced to a common ancestor. Clinically the disease was characterized by congenital lateral recumbency, opisthotonos, extension of the limbs, normal to increased reflexes, and normal alertness. At histological examination dysmyelination occurred constantly in specific spinal tracts.