The purpose of this prospective randomised double-blind study was to determine the effective dose of propofol required for the successful first attempt insertion of the laryngeal tube compared with the laryngeal mask airway in patients co-induced using alfentanil 5 microg.kg(-1), undergoing short elective gynaecological procedures. The first patient in each group received propofol 2.5 mg.kg(-1) for induction. In accordance with Dixon's up-and-down method, the dose of propofol for consecutive patients in each group was varied with increments or decrements of 0.5 mg.kg(-1) based on the previous patient 'all-or-none' purposeful movement response to first attempt of insertion of the randomised device. The ED50 (SD) of propofol was 2.66 (0.86) mg.kg(-1) and 2.33 (0.37) mg.kg(-1) for the laryngeal tube and laryngeal mask patients, respectively, which did not reach statistical significance (p = 0.40). We conclude therefore that the insertion of the two airway devices requires similar bolus doses of propofol when alfentanil is used as the co-induction drug.