1. Serum concentrations of amoxycillin and clavulanic acid were measured in patients with end-stage renal disease (ESRD) following intravenous administration of 1.2 g Augmentin. Augmentin was administered on a non-dialysis day and 2 h prior to a 4 h dialysis session. 2. The mean values of total serum clearance, mean residence time, volume of distribution at steady state, and terminal half-life for amoxycillin on the non-dialysis day were 14.4 ml min-1, 19.2 h, 14.9 l and 13.6 h, respectively. 3. The mean values of dialysis clearance, total serum clearance during dialysis, fractional drug removal during haemodialysis and half-life during dialysis for amoxycillin were 77.1 ml min-1, 91.5 ml min-1, 0.64 and 2.30 h, respectively. 4. The mean values of total serum clearance, mean residence time, volume of distribution at steady state, and terminal half-life for clavulanic acid on the non-dialysis day were 43.6 ml min-1, 4.4 h, 11.0 l and 3.05 h, respectively. 5. The mean values of dialysis clearance, total serum clearance during dialysis, fractional drug removal during haemodialysis and half-life during dialysis for clavulanic acid were 92.8 ml min-1, 136 ml min-1, 0.65 and 1.19 h, respectively. 6. The total serum clearance on the non-dialysis day, which represents non-renal clearance, was lower than that in normal subjects for both amoxycillin and clavulanic acid. These data would suggest some degree of hepatic impairment in patients with ESRD.(ABSTRACT TRUNCATED AT 250 WORDS)