The rate of colorectal tumors causing large bowel obstruction is still high (about 16%). In our experience, 93 out of 985 patients (9.4%) affected by colorectal cancer required surgery because of large bowel obstruction. The comparative analysis between 64 (68.8%) obstructed and 738 (82.7%) non-obstructed radically resected patients showed that sex and age of patients, tumor site, tumor diameter, parietal infiltration, grading, lymphnode involvement, distant metastases, and staging were not significantly different. Post-operative mortality rates (1.6% vs. 0.5%) and morbidity rates (15.6% vs. 15.6%) were not significantly different as well. On the contrary, survival rate was different. Patients submitted to radical resections had a far poorer prognosis as compared with non-obstructed radically resected ones: the five-year survival was 41.2% and 78.9% respectively. Radically resected obstructed patients showed an higher and earlier ráte of local and distant recurrence with a disease-related death rate of 47.6% vs. 16.3% as compared with non-obstructed ones. The occlusive phenomenon by itself resulted to represent an independent unfavorable factor negatively affecting long term prognosis after radical resections.