Urease plays an important role in the urea metabolism and the effect of urease activity on human and environment is enormous. For instance, urease acts as a virulence factor of the urinary and gastrointestinal tracts infections in human and animal, being involved in kidney stone formation, catheter encrustation, pyelonephritis, ammonia encephalopathy, hepatic coma, and urinary tract infections. Widespread urease activity in soil induces a plant damage due to ammonia toxicity and pH increase. Therefore, urease activity regulation through urease inhibitors would lead to an enhanced efficiency of urea nitrogen uptake in plants and to the improved therapeutic strategies for ureolytic bacterial infections. To search for new inhibitory compounds on urease activity from herbs, MeOH extracts of herbs were screened. Among them, the MeOH extracts of Areca catechu exhibited an excellent inhibitory effect on urease activity. Two compounds were isolated from the Et acetate fraction by the activity guided fractionation. Their chem. structures were identified as (+)-catechin (compound I) and allantoin (compound II) by spectroscopic evidence, resp. Compound I showed a stronger inhibitory effect on urease activity than compound II.