We determined the effective time to satisfactory intubation conditions after the administration of rocuronium 0.6 mg.kg-1 to 120 unpremedicated adult patients anaesthetised with propofol 2.5 mg.kg-1 or thiopentone 5 mg.kg-1. Intubation conditions were assessed in 10 subgroups of 12 patients at 30, 40, 50, 60 and 70 s. The effective times to satisfactory intubation conditions in 50 and 90% of patients were obtained by the method of maximum likelihood after log time-probit response transformations. Intubation conditions after induction of anaesthesia with propofol were satisfactory in 5/12 patients at 30 s, 7/12 at 40 s, 10/12 at 50 s, 11/12 at 60 s and 11/12 at 70 s compared with 1/12 patients at 30 s, 2/12 at 40 s, 5/12 at 50 s, 7/12 at 60 s and 8/12 at 70 s after induction with thiopentone. The effective times to satisfactory intubation conditions in 50% and 90% (95% confidence intervals) of patients after rocuronium 0.6 mg.kg-1 were 34 (26-40) s and 61 (50-81) s in patients given propofol compared with 57 (48-69) s and 101 (79-167) s in patients given thiopentone. We conclude that rocuronium 0.6 mg.kg-1 may be a suitable alternative to suxamethonium during rapid sequence induction of anaesthesia with propofol in situations where suxamethonium is contraindicated.