The kallikrein content in human mixed saliva was 1-2 Frey Units (FU)/ml. Acetone dried powder of saliva was suitable and sufficient for storage as the starting material of the following purification. Diethylaminoethyl-cellulose adsorption batch wise method as the 1st step of purification yielded high recovery of activity and excellent reproducibility. Acrinol precipitation and carboxymethyl-cellulose methods were good also, with inconsistent results, depending on the constituents of the starting materials. Purification 15-26 times increase and purity index 13-31 FU/mg were obtained with acetone fractionation. Treatment at 55[degree]C, 5 min., pH 6.0, was not effective on kallikrein activity but seemed to be destructive for kallikreinase. Purified preparation 165 FU/OD280 was successfully obtained by sephadex gel filtration with the good yield. Biological purity (FU/mg) did not always agree with esterase activity/mg within the crude preparations.