Objective： To evaluate the prognostic value of chemotherapy-induced neutropenia (CIN) in metastatic colon cancer undergoing first-line chemotherapy with FOLFOX. Methods: Data were collected from a retrospective survey of 158 consecutive metastatic colon cancer patients who had undergone FOLFOX chemotherapy. The clinicopathological characteristics and chemotherapy features of the patients were analyzed as potential prognostic factors. The patients were stratified by the decreased level of CIN to three groups: large decreased level (the number of neutrophil decreased more than 1.0×109 compared with that before chemotherapy),small decreased level (the number of neutrophil decreased less than 1.0×109 compared with that before chemotherapy) and the absence of neutropenia. Results: According to a multivariate COX model, decreased level of CIN was a independent prognostic factor of colon cancer patients. Hazard ratios of death were 0.687 (95% CI: 0.381-0.812, P=0.016) for patients with large decreased level of CIN and 0.817 (95% CI: 0.527-0.939,P=0.027) for those with small decreased level of CIN compared with those of absent neutropenia patients. Median overall survival was 12.9 months (95% CI: 10.4-15.4) for patients without neutropenia (A) compared with 20.8 months (95% CI: 18.3-23.1) for patients with large-decreased level of CIN (L) and with 17.3 months (95% CI: 16.2-18.8) for those with small-decreased level of CIN (S vs. L, P=0.018; L vs. A, P=0.009; S vs. A, P=0.011). Conclusion: Our results demonstrate that the decreased level of CIN is a predictor of prognosis in patients with metastatic colon cancer undergoing FOLFOX chemotherapy. Patients who have experienced large decreased level of CIN haave longer survival time than small decreased level of CIN or absent patients. To monitor CIN decreased level timely and adjust chemotherapy drug dose may help improve the prognosis.