Abstract: The present invention relates to the detection of B. gingivalis by the specific ability of B. gingivalis to hydrolyze N-carbobenzoxy-glycyl-glycyl-L-arginine-B-napthylamide derivatives. The present invention also relates to the use of assay systems which inhibit serum amino peptidase and enhance the detection of the B. gingivalis N-CBz-Gly-Gly-Arg peptidase. The assay system inhibits the serum enzyme by the use of a serum aminopeptidase inhibitor which inhibits the activity of serum aminopeptidase to a greater extent that it inhibits the activity of B. gingivalis N-CBz-Gly-Gly-Arg peptidase. The assay system also increases the reliability of detection of the B. gingivalis enzyme by the use of enhancing materials which enhance the enzyme activity of B. gingivalis N-CBz-Gly-Gly-Arg peptidase to a greater extent than such materials enhance the enzyme activity of serum aminopeptidase.