Background: Transoral endoscopic suturing is now being evaluated in the treatment of gastroesophageal reflux disease. This novel procedure involves the placement of sutures into the proximal cardia, with extra-corporeal knot tying and creation of a gastric plication using a knot pusher and cutter. This endoscopic valvuloplasty has been shown to be safe and efficacious in early human clinical trials. A study of the depth of suture placement would further contribute to the understanding of this new technique. Methods: An investigation into the placement and depth of endoscopically placed gastric sutures was conducted in the stomachs of 4 farm pigs. Two of these studies were conducted in live anesthetized farm pigs (50-60lbs) and two in stomachs obtained at slaughter from farm pigs (about 200 lbs). The tissue into which the suture is placed is suctioned into the sewing capsule mounted at the distal end of a standard upper endoscope. After creating endoscopic knots, tissue samples containing a suture were frozen till firm, then trimmed to allow visualization of the deepest part of the suture. Measurements were obtained using a dissecting microscope. Photos were obtained of each suture in place within the tissue. Results: In the first stomach on a live animal, suture depth was compared using 10 seconds (2.5 mm +/-0.72, 8 sutures ) and 30 seconds (3.0 mm +/- 0.93, 8 sutures) of vaccum time. This minor difference was not significant (p=0.44). Stomach thickness associated with these sutures averaged 8.62+/- 2.8 mm). In the second live animal suture depth averaged 3.3 +/- 1.1 mm (6 sutures) with a tissue depth of 6.8+/-3.76 mm. Ten sutures were then placed in each of the two ex vivo stomachs. Suture depth averaged 3.31+/- 1.24 mm and 2.81+/- 0.43 mm respectively. Corresponding tissue thickness was 10.25 +/- 3.81 mm and 7.03+/- 1.19 mm. Overall, endoscopically placed sutures averaged a depth of 2.86+/- 0.91mm with a tissue depth of 8.11+/- 3.07mm. Most of the sutures were placed in the submucosal layer of the stomach. Some sutures entered the muscular wall. On three occasions, all of which were associated with gastric tissue thickness of < 5 mm, the suture penetrated the stomach wall. Conclusions: Increasing vacuum suction time beyond 10 seconds does not significantly affect depth of stitch. Knots created endoscopically have a suture depth mainly into the submucosal layer of the stomach. Stomach wall thickness may determine the depth of endoscopically placed sutures. Background: Transoral endoscopic suturing is now being evaluated in the treatment of gastroesophageal reflux disease. This novel procedure involves the placement of sutures into the proximal cardia, with extra-corporeal knot tying and creation of a gastric plication using a knot pusher and cutter. This endoscopic valvuloplasty has been shown to be safe and efficacious in early human clinical trials. A study of the depth of suture placement would further contribute to the understanding of this new technique. Methods: An investigation into the placement and depth of endoscopically placed gastric sutures was conducted in the stomachs of 4 farm pigs. Two of these studies were conducted in live anesthetized farm pigs (50-60lbs) and two in stomachs obtained at slaughter from farm pigs (about 200 lbs). The tissue into which the suture is placed is suctioned into the sewing capsule mounted at the distal end of a standard upper endoscope. After creating endoscopic knots, tissue samples containing a suture were frozen till firm, then trimmed to allow visualization of the deepest part of the suture. Measurements were obtained using a dissecting microscope. Photos were obtained of each suture in place within the tissue. Results: In the first stomach on a live animal, suture depth was compared using 10 seconds (2.5 mm +/-0.72, 8 sutures ) and 30 seconds (3.0 mm +/- 0.93, 8 sutures) of vaccum time. This minor difference was not significant (p=0.44). Stomach thickness associated with these sutures averaged 8.62+/- 2.8 mm). In the second live animal suture depth averaged 3.3 +/- 1.1 mm (6 sutures) with a tissue depth of 6.8+/-3.76 mm. Ten sutures were then placed in each of the two ex vivo stomachs. Suture depth averaged 3.31+/- 1.24 mm and 2.81+/- 0.43 mm respectively. Corresponding tissue thickness was 10.25 +/- 3.81 mm and 7.03+/- 1.19 mm. Overall, endoscopically placed sutures averaged a depth of 2.86+/- 0.91mm with a tissue depth of 8.11+/- 3.07mm. Most of the sutures were placed in the submucosal layer of the stomach. Some sutures entered the muscular wall. On three occasions, all of which were associated with gastric tissue thickness of < 5 mm, the suture penetrated the stomach wall. Conclusions: Increasing vacuum suction time beyond 10 seconds does not significantly affect depth of stitch. Knots created endoscopically have a suture depth mainly into the submucosal layer of the stomach. Stomach wall thickness may determine the depth of endoscopically placed sutures.