In a series of 260 consecutive X-ray mammography examinations in symptomatic patients, 25 patients proved to have breast cancer, and 41 had various benign breast conditions. In the 66 patients with abnormal mammograms a real-time ultrasound examination with a 7.5 MHz linear array transducer and a fluid offset pad was performed. This paper focuses on the ultrasound aspect of the skin and the subcutaneous fat layer in various benign and malignant breast conditions. In most of the malignant tumors studied as well as in cases of fat necrosis and breast abscesses, the following ultrasound signs were encountered: discontinuity of the sharp echogenic subcutaneous specular reflector, thickening of the skin, and locally increased echogenicity of the subcutaneous fat layer. In breast cancer these signs were seen in some patients with small tumors, in deeply located tumors as well as in patients with no skin retraction on clinical examination. The differential diagnosis between cancer and benign breast tumors cannot be based upon the ultrasound aspect of the skin and subcutaneous fat layer alone. X-ray mammography as well as clinical criteria and anamnestic factors should be used for the diagnosis of breast abscesses (calor, rubor, tumor, dolor) and for the diagnosis of fat necrosis (surgery, trauma).