The pharmacokinetics of ciprofloxacin were evaluated in 11 patients (3 patients with impaired renal function) with advanced liver cirrhosis after a single oral dose of 500 mg. Mean serum peaks were 2.80 +/- 1.00 mg.l in 64 +/- 37 min after intake in patients with normal renal function. Elimination was reduced in comparison with healthy volunteers: t1/2-beta 510 +/- 158 min with a total area under the curve of 18.2 +/- 10.3 mg x h/l. Mean recovery of the parent compound from urine was 38 +/- 9% of the dose. In 3 patients with cirrhosis plus poor renal function, elimination was markedly reduced. In patients under 60 years with good renal function, the standard dose does not require a reduction.