OBJECTIVE Some factors like stent wires, balloon dilatation and use of guide wires seems to increase perforation after self-expandable metal stent (SEMS) placement, but few studies mentioned about the relationship between angulation of malignant stricture and perforation. The present study aimed to confirm that more angular positioning of stents increases perforation. METHODS This study was conducted with retrospectively evaluation at Digestive Disease Center, CHA Bundang Medical Center, CHA University. Between January 2002 and August 2011, SEMS was inserted in 130 patients with malignant colorectal obstruction. We studied the difference in the angle of stenosis between perforation and non-perforation groups using fluorography images. RESULTS SEMS insertion was performed in 130 cases of obstruction due to colon cancer. Perforation occurred in eight patients (6.2%) of them. Thirteen cases were excluded from the analysis due to poor fluoroscopic images. Among the eight patients with perforation, the mean stenosis angle was 109.9° compared to 153.1° in the nonperforation group, indicating that the angle was more acute in the perforation group (p=0.016). CONCLUSIONS This study shows that more angular positioning of stent increases bowel perforation after SEMS placement for malignant colorectal obstruction.