The pharmacokinetics of trapidil were studied in 15 patients with chronic liver disease (12 with hepatic cirrhosis, 2 with alcoholic fatty liver, 1 with liver fibrosis). Trapidil was administered intravenously as a 100-mg bolus. Serum samples were analyzed for trapidil by means of high-performance liquid chromatography. Mean pharmacokinetic parameters were compared with those found in a previous study of 12 healthy volunteers. Total plasma clearance was decreased significantly in patients with hepatic cirrhosis (96 mL/ min versus 258 mL/min in healthy individuals and 252 mL/min in patients with noncirrhotic liver disease). No difference in clearance was observed between patients with compensated or decompensated cirrhosis, and portal hypertension did not affect this clearance of trapidil. It can be concluded that trapidil clearance is a parameter that is very sensitive to alterations in hepatic clearance caused by liver cirrhosis, and that the dosage of trapidil should be adjusted accordingly in such patients.