To determine the distribution of a kidney acid RNase (RNase K2) and other RNases, the levels of RNase K2, RNase A, and seminal RNase (RNase Vs1) in bovine tissues and body fluids were measured by enzyme immunoassay. The crude extracts of several tissues and body fluids were fractionated by phospho-cellulose column chromatography. The enzymatic activities at pH 7.5 and 6.0 and enzyme contents of each tube were measured by enzyme assay and enzyme immunoassay, respectively. In the pancreas, parotid gland, and heart, most RNase activity was due to a single peak of RNase A, but a small amount of RNase K2 was always observed. In the kidney, there was about 5 times as much RNase K2 as RNase A. In the lung, although RNase K2 and RNase A were the major components, there are another two alkaline RNase peaks. In the spleen and liver, there are four RNases, two acid RNases, one of which is RNase K2, and two alkaline RNases including RNase A. A new acid RNase (non RNase K2-acid RNase) from both organs was immunologically the same. In serum, there are at least four RNases. By partial purification of serum RNases by phosphocellulose and heparin-Sepharose column chromatographies, at least 4 RNases, RNase A, RNase K2 and the other two alkaline RNases, one of which is immunologically indistinguishable from liver alkaline RNase, were confirmed. The other serum alkaline RNase was immunologically related to lung and spleen alkaline RNases. In conclusion, in bovine tissues and body fluids there are at least 7 types of pyrimidine-base-specific RNases: brain RNase, seminal RNase, RNase A, RNase K2, an acid RNase (RNase BSP1), an alkaline RNase (RNase BL4), and another alkaline RNase in serum.