Collagen was isolated from a fossil bone of a sabre-toothed tiger femur from the La Brea tar pits, radiocarbon-dated at 12,650 B. P., and a rib bone from an Egyptian mummy, less than 3000 years old. Modern bovine bone showed characteristic collagen bands on gel electrophoresis in which the alpha components were resolved and higher molecular-weight dimers and trimers could be seen. However, both fossil bones showed a broad diffuse band, with no indication of the existence of alpha-chains or higher molecular-weight aggregates. Thus, there apparently is a broad range of molecular-weight residues present in the fossil collagen which has undergone degradation, but in which the amino acid composition has not been affected. -- AATA