After a short training programme 11 naval medical trainees inserted a laryngeal mask airway (LMA) and a tracheal tube (ETT) in random order in a total of 110 anaesthetised patients. They were allowed 40 s for each attempt. Success was defined as the detection of expired carbon dioxide within 40 s of Guedel airway removal which subsequently rose to an end-tidal value of at least 4 kPa, together with satisfactory lung expansion and ventilation, without other airway intervention by the anaesthetist. 104 LMA insertions were successful compared with 56 of ETTs (p less than 0.01). All first attempts at LMA insertion were successful, whereas satisfactory ETT placement was progressive. Insertion was also quicker with the LMA (20 s) than with the ETT (35 s) (p less than 0.01). Further studies are indicated to assess the value of the LMA in emergencies.