We studied 60 adult patients to assess if low doses of rocuronium improved conditions for tracheal intubation during induction of anaesthesia with propofol 2.5 mg kg-1 and alfentanil 10 micrograms kg-1. In a double-blind, randomized design, patients were allocated to one of three groups: group P = saline; group R1 = rocuronium 0.1 mg kg-1; and group R3 = rocuronium 0.3 mg kg-1. Intubation conditions were judged as optimal, suboptimal or failure, based on the scoring of ease of jaw opening and laryngoscopy, position of the vocal cords and degree of straining after tracheal intubation. Intubation conditions were judged as optimal in one patient in group P, in six patients in group R1 and in 18 patients in group R3. Conditions were judged as a failure in seven patients in group P, in one patient in group R1 and in none in group R3. No laryngospasm or other complications were observed in any patient. The addition of low doses of rocuronium significantly improved intubation conditions (P < < 0.001). Ventilation was controlled during surgery, and in no patient was any problem encountered with antagonism of neuromuscular block with neostigmine. Injection of rocuronium 0.3 mg kg-1 (ED95) with propofol and alfentanil provided a high proportion of optimal intubation conditions.