Objective To observe the ultrasonographic features of primary squamous cell carcinoma of the breast and its clinical and histopathological characteristics. Methods The ultrasonographic features, clinical and histopathological characteristics of 7 middle-aged women (median age 61 years old) with primary squamous cell carcinoma of the breast confirmed histopathologically from January 1995 to December 2014 in Peking Union Medical College Hospital were retrospectively reviewed. Results There were 8 lesions in seven cases. Six cases were single lesion and 1 case with multiple lesions, the diameters of the lesions were 7.0-60.0 mm [mean (34.0±19.6) mm]. On grayscale ultrasound, 6 lesions with solid compoments were hypoechoic, 2 lesions with solid and cystic compoments were complex echogenic, the lesions all had irregular shape and indistinct margin, 2 lesions had calcifications. On color Doppler flow imaging, 7 lesions had rich blood flow signals (Ⅱor Ⅲ) and 1 lesion had no blood flow signal. On gross histopathological examination, 6 masses were solid, pale-white colored, medium texture and the boundary was not clear. Two masses had cystic cavity. One old patient who was 70 years old had several times chest wall recurrence after mastectomy. On ultrasonography, the lesion showed an anechoic cyst with thick wall. Two chest wall recurrence lesions were cystic with thick wall. Microscopic examination showed squamous cell carcinoma infiltrating into the fiber adipose and skeletal muscle tissue. Conclusions Primary squamous cell carcinoma of the breast is more common in large tumor size. Ultrasound can show the more cysticcomponents of the tumor and abundant vascularity, which is helpful for diagnosis.