Background: Colon leakage score (CLS) was developed for risk prediction of anastomotic leak (AL) in the left-sided colorectal surgery. Although the risk factors for leakage are well known and accepted by the surgical community, an accurate forecast of AL is still a difficult task. Objective: The study aims to apply the CLS in patients undergoing left-sided colorectal surgery. Methods: Retrospective study in patients with the left-sided colorectal surgery and primary anastomosis without diverting stoma. CLS was calculated in patients, who were classified in AL and NO-AL groups. Predictive value of CLS was evaluated by receiver operator characteristic. Correlation between CLS and AL was determined. 208 patients (55% male, mean age 59 years) were included in the study. Results: Overall, AL was 7.2%. Mean CLS of all patients was 7.2 ± 3.2 (0-17). Patients with AL had a higher CLS (11.8 ± 2.3) than NO-AL patients (6.8 ± 3) (p = 0.0001). The area under the curve for the prediction of AL by CLS was 0.898 ([CI] 0.829-0.968, p = 0.0001). A CLS of 8.5 had 93% sensitivity and 72% specificity. There was a statistically significant odds ratio for CLS and AL (0.58: [CI] 0.46-0.73, p = 0.0001). Conclusion: CLS is a useful tool to predict AL in the left-sided colorectal surgery.