In a collection of udder of cattle obtained from slaughter house to study mastitis a case was diagnosed as intraductal carcinoma. At necropsy, the condition was not recognized grossly.Microscopically,the udder tissue showed tubular structures occupied a wide areas. The tumors was characterized by anplastic cell proliferation forming ductal and aciner structures, some of which had papillary projection. Signs of malignancy were prominent including pleomorphism, increased mitotic activity and hyperchromatism. On the basis of the histopathology, this type of tumor was diagnosed as adenocarcinoma. This case can be classified as "grade II".