There are many bovine congenital defects of unknown etiology, suspected etiology and known etiology. Congenital defects of known environmental etiology such as bovine virus diarrhea-induced cerebellar atrophy, or plant-induced deformity such as crooked-calf diseases caused by lupine, require changes in management procedures. Defects caused by genetic factors are of considerable concern to the AI stations, cattle breeders, and cattle breed associations. Initial diagnosis of congenital defects is frequently required of practicing veterinarians. Some of the genetic diseases of current concern to the cattle industry of the United States include congenital defects of the skin such as epitheliogenesis imperfecta, hypotrichosis, fragile skin, and protoporphyria. Of the internal organs, the reproductive system is of particular concern. Defects of bone are numerous and may affect single structures such as adactyly, tibial hemimelia, and syndactyly. Generalized skeletal defects of importance include dwarfism and osteopetrosis. Muscular defects of significance are doublemuscling and arthrogryposis. Furthermore, genetically-caused defects of the central nervous system need further attention, particularly internal hydrocephalus and mannosidosis. Many defects encountered of suspected etiology need close attention. In this category, as well as those of unknown etiology, practicing veterinarians remain the main source of information to guide further study.