OBJECTIVE In order to test the hypothesis that under the association propofol-alfentanil-IV lidocaine the trachea could be intubated easily without an additional muscle relaxant, this study compared the intubation conditions when this association was combined or not with vecuronium. METHODS Randomized comparative trial. METHODS The study included 152 young adults classified as ASA physical class I and Mallampati presentation grade 1, randomly allocated either into Vecu+ group or Vécu0 group, depending on whether vecuronium was co-administered or not. METHODS All patients received midazolam 0.05 mg.kg-1 i.v., one minute before induction. Those of group Vecu0 were given successively within two minutes: alfentanil 0.03 mg.kg-1, lidocaine 1.5 mg.kg-1 i.v. and propofol 2.5 mg.kg-1. Patients of group Vecu+ received similar doses of alfentanil and propofol as well as vecuronium 0.08 mg.kg-1. The endotracheal tube was inserted one minute after induction in the patients of Vecu0 group, and after three minutes in those of the Vecu+ group. During intubation, scores of mouth opening, glottis opening and coughing were established, in order to assess intubation conditions. RESULTS Similar convenient intubating conditions were obtained in both groups (in 97% of patients in Vecu+ group vs 95% of those in Vecu0 group). In the latter, the glottis opening was less pronounced. CONCLUSIONS In young healthy adults, without anaesthetic risk (emergency, full stomach) and without foreseen difficult intubation, the endotracheal tube can be inserted in convenient conditions without a muscle relaxant, under the association propofol-alfentanil-lidocaine iv.