The aim of this prospective trial was to evaluate if 3-D ultrasound (US) brings any advantage to breast diagnostics. A total of 65 women with breast lesions (42 malignant, 23 benign) were examined preoperatively with 2-D and 3-D US. The impact of the use of the 3-D coronal plane for the visualization of the infiltrative zone in comparison to 2-D US was evaluated. Additionally, 3-D surface imaging and volumetry were performed. The coronal plane was of benefit when the infiltrative zone was unclear (6 of 8 cases) or not visible (17 of 39 cases; 43.6%) using 2-D imaging. The surface mode was advantageous for imaging complex structures (e.g., a multinodular fibroadenoma). Volumetry yielded a highly significant correlation between 2-D and 3-D US. 3-D US of breast lesions as adjunct to 2-D sonography can offer a better assessment of the infiltrative zone. Moreover, it enables accurate documentation of data.