Alfentanil-propofol combination provides adequate conditions for tracheal intubation without neuromuscular blocking drugs in most patients. Providing an option for intense opioid effect without compromising recovery after short operations, remifentanil might offer benefits over alfentanil, especially in ambulatory surgery. In this study intubating conditions after remifentanil-propofol were compared to those after alfentanil-propofol. In a randomized, double-blind study 60 healthy patients were assigned to one of three groups (n=20). After intravenous atropine, remifentanil 3 or 4 microg kg(-1) (Rem3 or Rem4) or alfentanil 30 microg kg(-1) (Alf30) was injected over 30 s followed by propofol 2.5 mg kg(-1). Sixty seconds after the administration of propofol, laryngoscopy and intubation were attempted. Intubating conditions were assessed as excellent, good or poor on the basis of ease of ventilation, jaw relaxation, position of the vocal cords, and patient response to intubation and slow inflation of the endotracheal tube cuff. Overall conditions at intubation were significantly (P<0.05) better, and the frequency of excellent conditions was significantly (P<0.05) higher in the Rem4 group compared with the Alf30 group. Intubation was judged to be impossible in 20%, 25% or 5% of the patients in the Alf30, Rem3 or Rem4 groups, respectively. No patient manifested signs of opioid-induced muscular rigidity. In terms of arterial pressures or heart rate, there were no differences between the groups. The best method was the combination of remifentanil 4 microg kg(-1) and propofol 2.5 mg kg(-1). This provided satisfactory intubating conditions in 93%, and prevented cardiovascular intubation response.