Abstract: Objective To evaluate the efficacy and safety of S-1 monotherapy in elderly patients with advanced breast cancer. Methods Retrospectively analysis sixty-five elderly patients with advanced breast cancer. The study group(S group,n=32):S-1：40-60 mg(＜1.25 m²，40 mg; 1.25-1．5 m²，50 mg;＞1.5 m²,60 mg， twice/day, oral administration，d1-d14, three weeks was a cycle. The control group(X group,n=33): Capecitabine ：2 000 mg/（m²·d）, separated to twice, d1-d14, three weeks was a cycle.The efficacy and toxicity were evaluated by WHO standards after 2-cycle treatment．Results The efficacy and toxicity could be evaluated in the all 65 patients,the RR of S group and X group was 31.3％(10/32)，27.3％(9/33),the DCR was 78.1％（25/32），69.7％(23/33）, the median TTP was 7.5 ，7.0 months， the OS was 17.3，15.2 months . There was no significant difference（P＞0.05）.The most common toxicities of the two groups were hematological，digestive toxic reactions， stomatitis and feeble，mainly 1-2 degree，and could be well tolerated．The Hand-foot syndrome rate of X group exceeded the S group（P=0.000）. Conclusion The efficacy of S-1 for elderly patients with advanced breast cancer is significant with well- tolerated toxicity better than Capecitabine，and worth to further study and popularize.