Twenty ASA I-II patients received either 2 or 3 x ED95 doses of rocuronium bromide during nitrous oxide, oxygen, propofol, fentanyl-based anaesthesia. The mean times to maximum block were 98 s and 74 s and the mean duration of clinical relaxation (recovery to 25% T1) was 35 min and 46 min following 620 micrograms kg-1 and 930 micrograms kg-1, respectively. Neuromuscular blockade was antagonized with either neostigmine or edrophonium from a twitch height of 25%. Although there was no significant difference between the recovery times neostigmine appeared to give more consistent antagonism of rocuronium-induced blockade.