The purpose of this study was to evaluate the effect of high hydrostatic pressure (HHP) on the enzyme activities in Saccharomyces cerevisiae (ATCC 16664) and Escherichia coli (ATCC 11229). Enzyme activities before and after HHP treatment were determined using an APIZYME enzyme assay kit. Thirteen active enzymes were detected in S. cerevisiae and E. coli. Pressure treatment at 448 MPa for 30s at 23 degrees C resulted in different effects on enzymes in S. cerevisiae and E. coli. HHP completely inactivated lipase, cystine arylamidase, and chymotrypsin and moderately inactivated esterase, esterase lipase, leucine arylamidase, valine arylamidase and alpha-glucosidase in S. cerevisiae. In E. coli, esterase, esterase lipase, lipase, valine arylamidase, cystine arylamidase, trypsin, alpha-glucosidase, and beta-glucuronidase were completely inactivated and leucine arylamidase and beta-galactosidase retained partial activities. Phosphoric hydrolases were not inactivated in both microorganisms. The use of the enzyme assay kit provided rapid and useful information on the microorganisms' enzymes and their sensitivity to HHP treatment in a simple manner.