Aminopeptidase activity associated with human buccal tissue and primary cultures of hamster buccal epithelium homogenates was assayed fluorometrically using 4-methoxy-2-naphthylamides of leucine, alanine, and arginine. Kinetic parameters, Km and Vmax, for all substrates were estimated. Aminopeptidase parameters for human tissue were similar to those for the in-vitro system and reported literature values for rodent buccal tissue aminopeptidases. Aminopeptidases of both tissues were also found to be similarly sensitive to typical inhibitors, bestatin and puromycin. Overall results suggest that appropriate in-vitro systems derived from animal tissues may be useful in assessing the role and localization of peptidases associated with buccal tissue.