Abstract: ?-Chymotrypsin inhibitors of thiourea class are reported that could be potent inhibitors of proteases, elastases, proteasomes, NS3 and NS4 serine protease of hepatitis C virus, dengue virus, etc. Compounds 1-22, which are belong to thiourea class, showed good inhibition. Their kinetics study and cytotoxicity profiles showed all type of inhibition except uncompetitive-type inhibition and no cytotoxicity except few compounds. Competitive type of inhibitors could inhibit other ?-chymotrypsin-like serine proteases, which are therapeutics target.