The technique of ultrasound tomography was tested in nearly 200 patients at our institute and was compared to mammography; therefrom additional information was obtained for the differentiation of tumors, the site of which had been unfavorable to mammography. Differential diagnosis of solid tissues and cysts also is possible in this way, especially in voluminous breasts which are a difficult case for palpation examination. Ultrasound may be helpful, too, in localization for exact puncture. As the final images have shown, gray-scale technique offers new possibilities, mainly with the single-scan taking less time and having undoubtedly a better resolving power. In diagnostics of early cancer or carcinoma in situ, of which, naturally, palpation findings are not existent, the method is inferior to mammography and certainly not yet satisfying. Even in the case of a known early carcinoma, having been localized by means of a positive mammogram, no sonographic correlative can as yet be found. At present, ultrasonic diagnostics is insufficient as a sole method for examination of the female breast; the technique is evidently useful, however, in case of special problems.