Recent data suggest that plasma P-selectin, an adhesion molecule, may be a clinically useful marker for thrombosis. Hepatic vessel thrombosis is one of the most serious complications following liver transplantation. To assess the contribution of the soluble P-selectin to this complication, we measured plasma P-selectin levels in 32 orthotopic liver transplantations, pre-, intra-, and post-operatively. We found that levels of circulating P-selectin were not different between cirrhotic patients and healthy subjects. Of the 32 patients, 8 had vascular complications. We found a significant increase in the plasma P-selectin concentration in the thrombotic group in early postoperative period compared with the non-thrombotic group (p < 0.002). It measurement may facilitate the diagnosis of thrombosis in the early postoperative period after liver transplantation, and therefore the management of these patients.