Abstract: Objectives: To discuss the influence of the number of lymph nodes retrieved on the prognosis of colorectal cancer of Dukes' stage B and C. Methods: Clinicopathologic features of 373 patients with colorectal cancer of Dukes' stage B and C were retrospectively reviewed. The relationship between the number of lymph nodes retrieved and prognosis of these patients was analyzed. Results:The mean number of recovered lymph nodes in all colorectal cancer patients was 13.71± 9.38. Tumor site, tumor size and depth of invasion influenced the number of lymph nodes retrieved. The average number of retrieved lymph nodes in colon cancer patients was 17.51± 12.79; whereas in rectal cancer patients it was 11.09± 6.17 (P=0.000). The 5- year survival rate for patients with fewer lymph nodes (0~10) retrieved was 60.4%, lower than the 77.5% for patients with more lymph nodes retrieved (≥10).The number of lymph nodes retrieved did not affect the prognosis for Dukes' stage C patients. If the number of retrieved lymph nodes was lower than 9 in rectal cancer patients or lower than 13 in colon cancer patients, the 5- year survival rate was dramatically decreased. Conclusion: A minimum number of 9 lymph nodes in rectal cancer patients and 13 lymph nodes in colon cancer patients should be removed to obtain the best prognosis.