An automatic purse-string device was compared with the traditional hand-sewn method in stapled oesophageal anastomosis. Fifteen greyhound dogs underwent distal oesophagectomy with stapled gastro-oesophageal anastomosis; a purse-string suture was used to draw the distal oesophagus around the stapling device. The animals were randomized into group 1 (n = 8), in which the automatic device was used, and group 2 (n = 7), in which the oesophageal purse string was hand-sewn. The automatic device failed to incorporate the oesophageal mucosa and submucosa reliably into the anastomotic staple line. There were five defective anastomoses in group 1 and none in group 2 (P = 0.037). Anastomotic bursting pressures were significantly reduced in group 1 compared with group 2 (median (range) 47 (22-110) versus 82 (68-88) mmHg, P = 0.032). Within group 1, a significant difference in bursting pressure existed between complete anastomoses and those in which the mucosa was not fully incorporated (median (range) 75 (60-110) versus 39 (22-50) mmHg, P = 0.037). Median (range) breaking strengths where anastomoses were incomplete were lower than where all layers were incorporated (1420 (1250-2220) versus 1990 (1590-2475) g/cm, P = 0.009). This study questions the safety of the automatic purse-string device for oesophageal anastomosis when used in accordance with present recommendations. Further evaluation and possibly modification of either the instrument design or the methods recommended by the manufacturer for its use are warranted.