Background and Objectives: As infraclavicular lymph node metastases is one of the parameters of stage III-C, the diagnostic techniques aiming to identify the metastases of this region have gained importance recently. In this study, we investigated the presence of axillary and infraclavicular lymph node metastases with ultrasonography. Methods: Axillary and infraclavicular lymph nodes were evaluated by preoperative ultrasonography in 100 consecutive breast cancer patients. Median age was 47 (23-76) years. Results: Ultrasonography identified lymph nodes correlating with metastases in the infraclavicular region in 20 patients. In 19 of these patients, metastases were verified in the lymph nodes with histopathologic examination (false positivity rate 5%). Of the 80 patients who were not considered as having metastases by ultrasonography, 59 had no metastatic lymph nodes on histological examination. The specificity of ultrasonography in the identification of metastatic lymph nodes in the infraclavicular region was 98.3%, with a sensitivity of 47.5%, positive predictive value of 95%, negative predictive value of 73.7%, and overall accuracy of 78%. Conclusions: Patients who were identified to have infraclavicular lymph node metastases by preoperative ultrasonographic examination should have a relevant treatment plan as they are classified as locally advanced, stage III-C disease.