The pharmacokinetics of paracetamol were studied in 11 patients with cirrhosis of the liver and 12 controls. The average biological half-life after oral administration of 1 g paracetamol was significantly prolonged in patients with hepatic cirrhosis compared to the controls (3.7 hr vs.2.1 hr) and, correspondingly, the average plasma clearance was significantly reduced from 337 ml x min-1 in the controls to 162 ml x min-1 in the patients with cirrhosis of the liver. After subchronic dosing of paracetamol with 1 g paracetamol t. i. d. the plasma half-lives of paracetamol remained unchanged. Steady-state levels of paracetamol were significantly increased in the patients with cirrhosis of the liver. A significant correlation between the values of plasma clearance of paracetamol and prothrombin time (r = +0.88), galactose elimination capacity (r = +0.66), plasma albumin (r = +0.85) was found. No clinical or biochemical signs of hepatotoxicity were observed during the study.