A computerized system differentiating cervical lymph nodes on ultrasonography as malignant or benign was developed from a database of 210 cases. Ten quantitative features representing sonographic features of size, margin, nodal border, shape, medulla ratio, medulla distribution, echogenicity, echogeneity, vascular density, and vascular pattern, were respectively calculated under the node contour segmented by an improved snake model. A rough margin based support vector machine was trained to distinguish between malignant and benign nodes using the 10 computerized features. The receiver operating characteristic (ROC) analysis was used to evaluate the performance. The developed system showed the normalized area under the ROC curve (Az, which is used as a summarized measure of the accuracy, ranges from 0.5 to 1.0) of 0.892. Compared with the radiologist's performance of Az of 0.784 this system has the potential to be an aid to radiologists in the task of distinguishing between malignant and benign cervical nodes on ultrasonography.