Study of spontaneous disorders in lower animals provides information more relevant to human disease than does laboratory-induced disease. A number of fascinating spontaneous models for human disease are delineated, viz, systemic lupus erythematosus in dogs and mice, porphyria in cows and pigs, atopic disease in dogs, Chediak-Higashi syndrome in the mink and partial albino cattle, cyclic neutropenia in the dog, and balding in a primate other than man. Study of animals should bring forth basic information affording clearer concepts of pathogenesis, as well as a more meaningful approach to therapeutic trials, of these and related diseases in many species.