Posterior lenticonus is a congenital defect of the posterior lenticular surface. The posterior cortical and capsular regions of the lens have a circumscribed conelike or globular protrusion of variable size. Opacities may be present in the region of the conus. The defect has been reported in man, rabbits, calves and mice. This report documents 2 cases in unrelated dogs. The possible mechanism for the formation of this defect is discussed.