Abstract: Objective To investigate the accuracy rate of ultrasound-guided core needle biopsy（CNB）in diagnosis of nonpalpable breast lesions less than 1 centimeter. Methods Clinical and pathological data of consecutive 124 female patients underwent CNB and surgical excisions were reviewed from January 2010 to July 2015. Results Among 124 patients，29 cases of breast cancer and 95 cases of non-cancer were diagnosed by CNB. The CNB diagnosis of all 29 breast cancer cases and 84 non-cancer cases were consistent with surgical diagnosis，and the coincidence rate was 91.1％（113/124），with Kappa value of 0.781（P＜0.001）. The remaining 11 cases diagnosed non-cancer by CNB were confirmed breast cancer by surgical excision，of which，10 cases were histological underestimate，and 1 case was false negative. Conclusion Ultrasound-guided CNB diagnosis is a simple and accurate method for breast lesions less than 1 centimeter.