BACKGROUND: The success of natural orifice surgery depends on a reliable, secure closure of the opening in the gut. Few tests of the integrity of these closures have been published. OBJECTIVE: To determine whether a gastrotomy can be closed safely and effectively from within the stomach by using looped T-anchors-a novel, endoscopically placed device. DESIGN: Head-to-head comparison trial of 2 closure methods in 9 explanted porcine stomachs. SETTING: Animal laboratory. INTERVENTION: Paired gastrotomies were made in porcine explants. One was closed by using endoscopic clips, and the other was closed by using modified T-anchors in a purse-string fashion. MAIN OUTCOME MEASUREMENTS: Gastric transmural pressure gradients at bursting of these closures were measured while the explanted stomachs were inflated with a high-pressure insufflator. RESULTS: The mean burst pressure of the looped T-anchors was 27.3 mm Hg, whereas that of the clip closures was 14 mm Hg. By using 10 mm Hg as a threshold for a "secure" closure, 7 of 9 clip closures failed to meet the threshold value, whereas all 9 of the T-anchor closures met or exceeded the threshold value (P = .0023, 2-tailed Fisher exact test). LIMITATION: Nonsurvival study. CONCLUSION: Looped T-anchors provide a secure gastric closure for natural orifice surgery and are superior to endoscopic clips for this purpose.