To define the molecular structure of bovine lens epithelium and its anterior lens capsule, we investigated the composition of lens capsule basement membrane proteins. Immunofluorescence and immunogold techniques were used to demonstrate the presence of type I and type III collagen in the lens capsule and in primary explant epithelial cultures grown on protein-binding membranes. Immunofluorescence staining with specific antibodies indicated that type I and type III collagen were constituents of lens basement membrane. We observed that deposition of type III collagen was more than type I collagen. The synthesis of fibrillar collagen by lens epithelium and its deposition in the lens capsule was established by localization of fibrillar collagen by transmission immunoelectron microscopy. These results demonstrate for the first time that normal lens epithelium synthesize fibrillar collagen which is an intrinsic component of the anterior lens capsule basement membrane.