The production of eleven hydrolytic enzymes of anaerobic bacteria namely : beta-lactamase, chondroitin sulfatase, collagenase, deoxyribonuclease, fibrinolysin, gelatinase, heparinase, hyaluronidase, lecithinase, lipase and phosphatase were determined. The bacterial strains were 77 strains isolated from various clinical specimens of 65 patients having been diagnosed to have anaerobic infection and 115 strains isolated from feces of 85 healthy adults. The enzymes which were valuable in taxonomy of certain organisms especially Clostridia were gelatinase, lecithinase and phosphatase. Beta-lactamase was found specifically for B. fragilis group. The production of chondroitin sulfatase, hyaluronidase, DNase, collagenase, fibrinolysin, heparinase, and phosphatase in patient isolates were higher than in control isolates of each anaerobic species. The role of these enzymes involving in infections process had been discussed.