The aim of the study was to present our experience with the use of intraoperative colonoscopy in patients with obstructing colon cancer in whom complete preoperative colonoscopy was not possible.Material and methods. We treated 480 patients with colon cancer from 2002 to 2008 in our department. In 80 patients (28 female and 52 male) we performed intraoperative colonoscopy due to obstructing colon cancer. Mean age of female patients was 67.8 yrs. (35-84 yrs.) and mean age of male patients was 66.5 yrs. (38-81 yrs.). In all of the patients preoperative complete colonoscopy was not possible.Results. Thanks to intraoperative colonoscopy we revealed new synchronous cancer lesions in 7 patients (8.75%) and therefore we extended the operation. In 28 patients (35%) we revealed polyps which, in 24 (85.7%) cases, were removed endoscopically and in 4 cases we decided to extend the operation.Conclusions. Intraoperative colonoscopy is efficient method in diagnosis of colon cancer especially in patients with obstructing colon cancer. Thanks to intraoperative colonoscopy patients with synchronous lesions may benefit from detection of lesions and avoid further operation.