Objective: To observe the variance of CRP level when patients with local advanced esophagus cancer receiving concurrent chemo-radiotherapy and to evaluate whether variance of CRP level relates to severity of radiation esophagitis. Method: from September 2012 to July 2013, 35 patients with local advanced esophagus cancer was treated by IMRT, intravenous infusion of cisplatin plus fluorouracil was taken concurrently. CRP level was measured before and one week after therapy. Radiation esophagitis was evaluated according to the Toxicity Criteria of RTOG. Results: CRP level significantly elevated from 16.9±11.2 mg/L measured before treatment to 25.34±11.65 mg/L measured one week after treatment (p < 0.05). The CRP level variance and the CRP level measured one week after treatment correlated to the severity of radiation esophagitis (p < 0.05). Conclusion: CRP level elevated when patients with local advanced esophagus cancer were treated with concurrent chemo-radiotherapy. The CRP level variance reflects the severity of radiation esophagitis to some extent.