The duration and possible accumulation of atracurium and pancuronium were studied in 59 patients (29 anephric and 30 normal) anaesthetized with 0.5% halothane in O2/N2O and supplemented by fentanyl. Equipotent doses of atracurium (0.5 mg–kg‐1) and pancuronium (0.1 mg–kg‐1) were given for intubation. Atracurium had a lower potency in anephric patients. The duration (first twitch response (TI) return to 20% of control) for atracurium was 28 min in anephric and 36 in normal patients. The corresponding mean times for pancuronium were 171 and 123 min, but with a very wide variation (range 20–380 min and 45–360 min, respectively). The duration of up to 8 incremental doses of atracurium (0.1 mg kg‐1) was 27 29 min in normal patients and of up to 13 increments was 25–34 min in anephric patients. Pancuronium (0.015 mg kg‐1) was given in a maximum of 4 increments. In normal patients the mean durations were 40–56 min, and in anephric patients 65–100 min. The duration of pancuronium, but not of atracurium, was prolonged with repeated injections (up to 2.7 times) in anephric patients. After pancuronium the spontaneous recovery was significantly slower in anephric patients, while the induced recovery was rapid and reliable in all groups. We conclude that atracurium is a safe and reliable muscle relaxant in normal and anephric patients, while pancuronium in both groups has a disturbing variation in duration and, in addition, signs of significant accumulation in anephric patients. The use of a nerve stimulator is mandatory.