A colony of carrier (10) and congenitally cataractous (11) Miniature Schnauzer dogs has been established. The clinical characteristics and course of the congenital cataracts are being documented by slit lamp biomicroscopic photography and a-scan ultrasonography. The immediate postnatal cataractogenesis is being studied histopathologically. Quantitative and qualitative characterization of the lens proteins and glutathione have been completed for the normal adult dog lens and for the adult cataractous lens. Similar studies are in progress for the normal and congenital cataractous puppy lenses. The protein kinetics of those normal and cataract adult and puppy lens are being defined. This study serves to establish the Miniature Schnauzer as a biomedical model for congenital cataract studies.