The complete amino acid sequence of basic FGF (146 residues) from ovine pituitary glands has been established. This has been achieved by the sequence analysis of subnanomole amounts of the intact molecule and of peptides derived by enzymatic digestions with clostripain, chymotrypsin, pepsin and Staphylococcus aureus V8 protease. Microbore HPLC, employing 1-2 mm i.d. columns, was used to purify, concentrate and buffer-exchange the FGF peptides. A novel application of ion-pairing chromatography was employed to isolate peptides which were not retained on conventional reversed-phase systems. There is only one positional difference between the ovine and bovine basic FGFs, but there are 3 positional differences between ovine and human basic FGFS.