NKCP is the completely refined protein layer from cultured Bacillus subtilis (natto) and is supplied in tablet form. It lacks the distinctive fermented odor and bacteria associated with fresh natto. Almost all vitamin K is removed during the manufacturing process. The main component of NKCP is the active fragment of Bacillopeptidase F, which is a serine protease secreted by Bacillus subtilis. In in vivo studies, NKCP shows fibrinolytic and amidolytic activity on plasmin specific synthetic substrate. Daily oral administration of NKCP in 28 volunteers for two weeks and then in 23 volunteers for several months, was examined. The fibrinolytic effect was demonstrated by a shortened euglobulin lysis time in both trials. Furthermore, we observed an improvement in shoulder stiffness. These results suggest that the oral administration of NKCP can be expected to have a fibrinolytic effect and cause positive changes in local blood flow. Further investigations may demonstrate NKCP to be useful in the prevention of thrombosis.