This study was conducted to find out the nature and the tenderizing ability for proteolytic enzymes such as papain and bromelin, from tropical plants, trypsin, from pancreas and microbial protease, from bacteria. Optimum pH and optimum temperature for enzymatic activity were investigated to find out the properties of each enzyme. The proteolytic activities in powdered nonfat beef and in chicken meat were estimated according to enzyme concentration and treated time in order to evaluate the tenderizing ability of each enzyme. The estimates of enzymatic activity by Anson method were 12.26, 13.80, 25.35, and 28.24 A.U. for papain, microbial protease, bromelin and trypsin, respectively. The optimum temperature for enzymatic action of papain, microbial protease, bromelin and trypsin were 50 degrees Centigrade, 50 degrees Centigrade, 60 degrees Centigrade and 40 degrees Centigrade, respectively. The optimum pH for enzymatic action of papain, bromelin, microbial protease was 7.0 while trypsis was 8.9. There was negative correlation between added enzyme concentration and treated time to tenderize a known amount of powdered non fat beef and chicken meat. The increasing order of prot eolytic activity found in powdered non-fat beef was; trypsin, microbial protease, bromelin and papain. The content of water-soluble protein and the waterholding capacity in chicken meat were increased by enzyme treatment but no significant differences in those abilities were found among the enzymes.