The clinical neuromuscular effects of two doses of vecuronium (0.15 mg kg-1 and 0.2 mg kg-1) were investigated in 20 healthy patients and 20 patients with cirrhosis, and compared with previous work in which vecuronium 0.1 mg kg-1 was given under identical conditions of anaesthesia and monitoring. Ten healthy patients received vecuronium 0.15 mg kg-1 and 10 received 0.2 mg kg-1. Similarly, 10 patients with cirrhosis received vecuronium 0.15 mg kg-1 and 10 received 0.2 mg kg-1. Vecuronium 0.1 mg kg-1 has previously been shown to have a somewhat shorter duration of action in cirrhotic as opposed to healthy patients. In this study, vecuronium 0.15 mg kg-1 was found to have a similar duration of action in both groups, and vecuronium 0.2 mg kg-1 had a significantly longer action in the cirrhotic group. It is suggested that vecuronium should be used with caution in patients with hepatic dysfunction and that, in such patients, monitoring of neuromuscular function is desirable.