The present role of rectal exploration in rectal cancer is defined. Indications and limitations of endoscopy and radiology in the study of colon relatively to the diagnosis and pre-treatment approach to rectal cancer, are reviewed. The need to establish definite parameters of tumor morphology indispensable to a correct surgical management, to a possible neoadjuvant therapy and to a precise assessment of the response to therapy, is emphasized. Compared results about the lengthwise tumor extent, the circumferential involvement of rectal walls and the distance from the internal anal sphincter, are reported. It is concluded that the two diagnostic examinations are complementary and that both represent excellent methods for the diagnosis and assessment of the extent of the disease.