The disposition kinetics of ofloxacin, a quinolone antibacterial agent excreted essentially unmodified by the kidney, was studied after single oral administration in 8 patients with compensated liver cirrhosis and in 8 control subjects. Mean elimination half-life and apparent volume of distribution were significantly increased in the cirrhotic group (7.6 vs. 4.9 h and 1.6 vs. 1.2 liters kg-1, respectively). A reduction in the renal clearance of ofloxacin was also observed in the cirrhotic patients, in spite of an apparently normal renal function. These observations indicate that also the pharmacokinetics of unmetabolized drugs may be altered in compensated liver cirrhosis. The serum concentration-time profiles of nearly all subjects exhibited a secondary peak 4-6 h after dosing. This double-peak behavior was interpreted as either enterohepatic circulation or biphasic gastric emptying of ofloxacin.