The kinetics of intravenous amoxicillin was studied in 8 patients with creatinine clearances of less than 7 ml/min who were on long-term hemodialysis. Kinetic parameters were determined using a 2-compartment linear model. The serum half-life (t1/2) of amoxicillin in these patients ranged from 7.5 to 21 hr. The t1/2 fell to 2.84 +/- 0.45 hr during dialysis. Approximately 30% of the dose was recovered in the dialysate during 4 hr of dialysis and there was a 25% reduction per hour in serum concentration. We present a dosage schedule for intravenous amoxicillin in patients with reduced renal function who are undergoing hemodialysis.