Total protein of small subunits of rat liver ribosomes was fractionated by chromatography on carboxymethylcellulose. Aliquots (between 5 and 30 mg) of the protein material of each peak were further separated by reversed phase liquid chromatography on an octadecasilyl silica column. In this way 15 of the 32 proteins of the small ribosomal subunit of rat liver could be isolated in milligram amounts.