Abstract: Objective:To evaluate the utility of ultrasound-guided fine-needle aspiration cytology before sentinel lymph node biopsy in breast cancer patients with clinically abnormal axillary lymph nodes.Methods:The final pathology and ultra -sound-guided fine-needle aspiration cytology results of 257 primary breast cancer patients with abnormal ultrasonographic axillary lymph nodes or palpable axillary lymph nodes seen in our hospital between October 2004to October 2010were ret rospectively analyzed. The enrolled patients had an ultrasound-guided fine-needle aspiration cytology examination before surgery or neo-adjuvant chemotherapy. If the cytology showed a positive result, axillary lymph node dissection or neo-adju-vant chemotherapy was performed. Otherwise, sentinel lymph node biopsy was performed. Results: Considering the final pathology, the ultrasound-guided fine-needle aspiration cytology had sensitivity, specificity, accuracy, positive predictive val-ue and negative predictive value of 76.3%,100 %,80.9%,100 % and 50.5%, respectively. Axillary lymph node metastases were accurately diagnosed with ultrasound-guided fine-needle aspiration cytology in 76.3% (158 /207 ) of the patients, and sentinel lymph node biopsy was avoided in these patients. Of patients with clinically abnormal axillary lymph nodes and negative ultrasound-guided fine-needle aspiration cytology, 50.5% (50/99) had no metastases in axillary lymph nodes, and axillary lymph node dissection could be avoided with sentinel lymph node biopsy. The sensitivity of the ultrasound-guided fine-needle aspiration cytology for patients with N1, N2 and N 3 node stage were 70.3%,93.6% and 100 %, respectively. The sensitivity of the ultrasound-guided fine-needle aspiration cytology for patients with T 1, T 2, T 3 and T 4 tumor size were 66.7%, 73.2%,91.7% and 100 %, respectively. Conclusion:Preoperative ultrasound-guided fine-needle aspiration cytology is a sim-ple, minimally invasive, and reliable technique for the initial evaluation of axillary lymph node status before sentinel lymph node biopsy in breast cancer patients with clinically abnormal axillary lymph nodes.