The incidence of iatrogenic colonic perforation has been gradually increasing. In particular, sigmoid colon perforations are difficult to handle because of excess mobility. The aim of this study was to evaluate the efficacy of the twin grasper-clips technique for large perforations of the sigmoid colon. This study was designed as a prospective, randomized, experimental study using ex vivo porcine colorectal specimens. Thirty standardized and variable artificial perforations were closed in the hemoclip group (hemoclips) and twin grasper group (hemoclips with a novel tissue grasper). We counted the number of hemoclips used per case to assess the cost and efficacy of the procedure. In the hemoclip group (n=15), among the 20-, 25-, and 30-mm defects, the mean number of clips (4.8±0.8, 6.0±1.6, and 8.4±2.1, respectively, p=0.011) and closure time (7.6±0.5, 9.9±3.3, and 13.9±4.1min, respectively, p=0.020) differed significantly. In the twin grasper group (n=15), among the 20-, 25-, and 30-mm defects, the mean number of clips (4.0±1.0, 5.0±0.7, and 5.4±1.1, respectively, p=0.101) and closure time (7.7±0.6, 8.3±1.9, and 9.1±2.7min, respectively, p=0.506) did not differ significantly. In 30-mm defects, the mean number of hemoclips used per case and total closure time were significantly lower in the twin grasper group than the hemoclip group. The twin grasper-clips technique seems to reduce the use of hemoclips and to result in more effective and rapid closure than does the conventional technique in large perforations of the ex vivo porcine sigmoid colon.