Proteins with known isoelectric points(pl), as determined by isoelectric focusing, are tabulated. When available, the native molecular weight and the submit molecular weight and stoichiometry are reported. For each entry, the source and, when applicable, the organ of origin and/or subcellular location are given. A previous table [P.C. Righetti and T. Caravaggio, J. Chromatogr., 127 (1976) 1–28] convered the years from 1966 (the intoduction of isoelectric focusing) to 1975. The present compilation spans the years 1976–1979 and contains approximately three times as many references and entries (>900).