A modified version of the Cormack and Lehane scoring system was prospectively evaluated in 663 patients requiring tracheal intubation. In the modified system, grade 2 (only part of the glottis visible) was divided into 2a (part of the cords visible) and 2b (only the arytenoids or the very posterior origin of the cords visible). One hundred and sixty-two intubations (24.4%) were scored as grade 2a and 43 (6.5%) as grade 2b, of which seven (4.3%) and 29 (67.4%), respectively, were difficult, defined as requiring more than one laryngoscopy or the use of specialist equipment. Grade 2b denotes a laryngoscopic view that is relatively common and is often associated with difficulty passing a tracheal tube. The modified scoring system thus provides more information than the original Cormack and Lehane system and its use should be considered when recording the ease of tracheal intubation in the anaesthetic record or in studies of tracheal intubation.