The flexible ultrathin fibreoptic laryngoscope allows placement of endotracheal tubes as small as 2.5 mm internal diameter. The purpose of this study was to document the safety and efficacy of intubation using an ultrathin fibreoptic laryngoscope. Proved safety and efficacy would justify the routine use of fibreoptic laryngoscopy in normal infants to maintain skills needed for management of the difficult infant airway. In this prospective study, 40 infants < 24 mo of age scheduled for elective surgery were randomly divided into two equal groups. After inhalation induction of anaesthesia, in 20 infants the trachea was intubated using direct rigid laryngoscopy, and in 20 using the ultrathin fibreoptic laryngoscope (size 1.8 mm OD) Olympus LFP. Time to successful intubation was recorded, as well as blood pressure, heart rate, end-tidal CO2 and oxygen saturation. Airway trauma in the operating room, the post-anaesthesia care unit, and on the first postoperative day was recorded. The intubation times using rigid laryngoscopy were less than those using fibreoptic laryngoscopy (13.6 +/- 0.9 sec (mean +/- SEM) vs 22.8 +/- 1.7 sec; P < 0.01). Oxygen saturation and end-tidal CO2 readings were not different between the two groups. After intubation, blood pressure and heart rate increased equally in both groups, returning to normal within one to two minutes. There was no difference in the airway trauma between groups. We conclude that the ultrathin fibreoptic laryngoscope is a safe and effective method for tracheal intubation in infants and may be used routinely in order to maintain fibreoptic airway skills.