OBJECTIVE: Evaluate the prognostic value of lymph node ratio (LNR) in patients undergoing resection of stage III colorectal cancer. METHODS: The clinicopathological and follow-up data were collected from 174 surgical patients with stage III colorectal cancer. The 5-year disease-free survival (DFS) and overall survival (OS) were evaluated using Kaplan-Meier method. The impact of LNR and clinicopathological factors on DFS and OS were evaluated using univariate and multivariate analysis. RESULTS: After a median follow-up of 62.5 months, the 5-year DFS and OS of the patients were 51.8% and 56.3%, respectively. The median number of lymph nodes harvested and the median number of positive lymph nodes examined were 10 and 3, respectively. The patients were stratified into 4 groups according to LNR quartiles (LNR1, LNR≤0.125; LNR2, 0.125<LNR≤0.260; LNR3, 0.260<LNR≤0.500; LNR4, LNR>0.500), whose 5-year DFS and OS were 64.2%, 53.5%, 41.8%, and 25.7% (P<0.05) and 68.1%, 60.8%, 49.2%, and 32.7% (P<0.05), respectively. Multivariate analysis identified age, T stage and LNR as the independent predictors of both DFS and OS. Subgroup analysis showed that LNR had an independent prognostic value on DFS and OS irrespective of the number of lymph nodes harvested. CONCLUSION: LNR is an independent prognostic factor for survival in patients with stage III colorectal cancer and is superior to the pN category in TNM staging.