We report here the rapid purification to homogeneity of a cyclic nucleotide-independent protein kinase sensitive to 5'6-dichloro-1-beta-D-ribofuranozylbenzimidazole (DRB), identical to the previously described casein kinase II, from lyophilized calf thymus by chromatography on phosphocellulose and Mono-Q FPLC columns.