INTRODUCTION:Transrectal natural orifice translumenal endoscopic surgery (NOTES) requires a good endoluminal view and adequate intrarectal bacterial clearance in the working area. We developed a new occlusion balloon unit with an easily detachable inflation device, which allows the surgeon a clear working area distal to the balloon. MATERIAL AND METHODS:The effectiveness of the sealing balloon and the extent of macroscopic and histopathological injury to the bowel wall at the site of balloon placement were examined in 12 pigs. RESULTS:The mean time to place and inflate the balloon unit was 12.0 ± 3.5 min, effective air-tightness lasted for 21.0 ± 12.0 min. There was no leakage of dye (methylene blue) past the balloon when pressure was maintained >6.70 ± 0.08 kPa (6.62-6.78 kPa). After gut irrigation, good visibility was maintained in the working area for six hours, and adequate bacterial clearance was maintained for three hours. There were no macroscopic signs of intestinal wall damage at the site of balloon placement. Histopathological examination showed only patchy mucosal damage and submucosal thrombus at the site of balloon placement. CONCLUSION:This newly-developed occlusion balloon unit helps to establish good visibility and adequate bacterial clearance for endoluminal surgical procedures.