Summary Type V collagen ( α 1 (V), α 2(V), α 3 (V)) was isolated from limited pepsin digests of bovine uterus. Fine purification of the protein was achieved by dialysis against Na 2HPO 4, pH 9.2 and phosphate buffered saline, pH 7.2. Resolution of the three chains was performed by ion-exchange chromatography: after separation of α 2(V) by DEAE-cellulose chromatography, α 1(V) and α 3(V) chains was resolved on CM-cellulose chromatography. The individual chains were characterised by SDS-poly-acrylamide gel electrophoresis, amino acid analysis and cyanogen bromide peptides. Comparison of the amount of α 3(V) chain with that of placental villi suggests that this collagen is mainly of uterine origin.