Objective To explore the clinical effects of S-1 single agent chemotherapy for the patients undergoing radical resection of cholangiocarcinoma.Methods The clinical data of 51 patients receiving radical resection of cholangiocarcinoma who were admitted to the Second Affiliated Hospital of Zhejiang University from November 2011 to December 2013 were retrospectively analyzed.After radical resection of cholangiocarcinoma,25 patients receiving non-special treatment and 26 patients receiving S-1 single agent chemotherapy were divided into the operation group and chemotherapy group,respectively.S-1 was taken orally twice per day.Forty mg/once of S-1 was applied to patients with the body surface area ＜ 1.25 m2,50 mg/once of S-1 was applied to patients with the body surface area ≥ 1.25 m2 and ＜ 1.50 m2,and 60 mg/once of S-1 was applied to patients with the body surface area ≥ 1.50 m2.The 14 days usage and 7 days withdrawal of S-1 were used as one course of treatment.The standard usage of S-1 was 6-8 courses of treatment.All the patients were followed up by outpatient examination and telephone interview till December 1,2014.Count data were analyzed using the chi-square test.Measurement data with normal distribution were presented as (x) ± s and analyzed using the t test.Survival curve was drawn by the Kaplan-Meier method,and survival analysis was done using the Log-rank test.Results Twenty-six patients in the chemotherapy group finished the courses of chemotherapy without chemotherapy-related death,and 14 patients had chemotherapy adverse reactions with remission after discontinuation of S-1.All the 51 patients were followed up for 5-37 months with a median time of 19 months.The median overall survival time,1-,3-year overall survival rates,tumor-free median survival time and 1-,3-year tumor-free survival rates were 22 months (range,18-27 months),72.3％,42.9％,21 months (range,16-26 months),60.0％,55.0％ in the operation group and 32 months (range,29-35 months),84.6％,44.4％,26 months (range,21-31 months),76.9％,61.9％ in the chemotherapy group,respectively.There was a significant difference in the overall survival between the 2 groups (x2=6.032,P ＜ 0.05).There was no significant difference in the tumor-free survival between the 2 groups (x2=0.498,P ＞ 0.05).Conclusion S-1 single agent chemotherapy after radical resection of cholangiocarcinoma could improve the survival of patients,while no obvious advantages of inhibiting tumor recurrence is observed.