To determine the influence of renal function on the pharmacology of atracurium, 10 patients with normal renal function and 10 with renal failure (scheduled for cadaver kidney transplant) were anesthetized with nitrous oxide and halothane. Atracurium besylate, 0.5 mg·kg−1, was given as an iv bolus and plasma samples were collected over a 4-h period. These samples were assayed for atracurium (all patients) and laudanosine, one of the principal metabolites (eight of the normal group), using an ion-exchange liquid chromatographic assay. The plasma concentrations of atracurium for each patient were fitted to a two-compartment pharmacokinetic model. The onset time, duration of action, and recovery time of atracurium neuromuscular blockade were measured. There were no differences found in the pharmacokinetics or pharmacodynamics of atracurium between patients with normal renal function and those with renal failure. There were measurable levels of laudanosine following atracurium administration with peak levels of 199 ± 31 ng·ml−1at 2 min. The authors conclude that the pharmacokinetics and pharmacodynamics of atracurium are not altered by renal failure.