Objectives-The purpose of this study was to establish a scoring system for predicting axillary lymph node metastasis (ALNM) in patients with breast invasive ductal carcinoma with negative axillary ultrasound (US) results. Methods-In this retrospective study, 156 breast invasive ductal carcinoma lesions from 156 women were retrospectively enrolled. The features of conventional US and contrast-enhanced ultrasound (CEUS) qualitative enhancement patterns and quantitative enhancement parameters were analyzed. Subsequently, a scoring system was created by a multivariate logistic regression analysis. Results-The results found that 60 patients (38%) showed ALNM. A scoring system was defined as risk score = 1.75 × (if lesion size ≥20 mm) + 1.93 × (if uncircumscribed margin shown on conventional US) + 1.77 × (if coarse or twisting penetrating vessels shown on CEUS). When the risk scores were less than 1.75, 1.75 to 1.93, 1.94 to 3.70, and 3.70 or higher, the risk rates of ALNM were 0% (0 of 9), 10.7% (5 of 46), 29.2% (14 of 48) and 77.4% (41 of 53), respectively. In comparison with conventional US alone, the scoring system using the combination of conventional US and CEUS showed better discrimination ability in terms of the area under the curve (0.830 versus 0.777; P = .037). Conclusions-A scoring system based on conventional US and CEUS may improve the prediction of ALNM. Key Words-axillary lymph node metastasis; breast invasive ductal carcinoma; contrast-enhanced ultrasound; conventional ultrasound B reast cancer ranks as the most prevalent type of cancer among women worldwide, accounting for nearly one-fourth of all cancers. 1 The most frequent histologic type of breast cancer is invasive ductal carcinoma (IDC). 2 In the absence of distant metastasis, axillary lymph node metastasis (ALNM) serves as an important prognostic indicator in patients with primary breast cancer. 3,4 The ALNM status can influence the clinical classification and decisions on treatment. Recent studies 5,6 have