Background. Many technical variations are possible in the placing and management of a double-lumen tube (DLT). We surveyed our practice to relate these variations to the course of the anaesthetic. Methods. We used a questionnaire to obtain details of technique in 506 consecutive double lumen intubations. The details were related to the incidence of secretions, tube displacement, and decreases of oxygen saturation (<88%) during one lung anaesthesia (OLA). Results. Robertshaw tubes were used for 482 of the 506 intubations. During OLA there were 48 instances of desaturation (<88%), 19 cases of upper lobe obstruction, 15 of carinal obstruction, 16 of isolation failure, eight of excessive secretions (none of whom had received an antisialogogue; P<0.01) and 12 miscellaneous events. The experience of the anaesthetist or use of a fibre-optic bronchoscope did not affect these events. Air was of no advantage as a maintenance gas. Atropine 400-600 mug appeared to prevent desaturation on OLA (P<0.05) but glycopyrrolate 200 mug did not. Conclusion. Most factors had little effect on the progress of the anaesthetic, but an antimuscarinic usefully reduced secretions, and atropine (but not glycopyrrolate) was associated with less desaturation during OLA.