Background: Emergency surgery for colon cancer is associated with high morbidity and mortality rates. Herein, this study was conducted to estimate the incidence and to detect the risk factors leading to mortality in cases of obstructed left colonic carcinoma. Methods: This prospective research included 150 patients diagnosed with obstructed left colon cancer and underwent surgical intervention. Based on the incidence of early mortality, they were divided into two groups; the survival and the deceased ones. Results: Mortality was encountered in 19 patients (12.67%). The deceased group showed older age and higher male predominance compared to the survived one. Likewise, the prevalence of heart and kidney disease was higher in the same group. The deceased patients expressed higher ASA and APACHE II scores before operation. These cases had a higher prevalence of shock and a longer duration of symptoms. The surgical intervention did not differ between the two groups. However, the incidence of perforation and intraabdominal free fluid was significantly increased in the deceased cases. In addition, the incidence of post-operative complications and duration of ICU admission significantly increased with mortality. Conclusion: Old age, male gender, ischemic heart disease, chronic kidney disease, ASA class III, shock, increased symptom duration, intraabdominal free fluid, tumor perforation, post-operative complications, and ICU admission were significant risk factors for mortality in such cases. Patients with one or more of the previous factors should be well evaluated to decrease the mortality risk.