Rectal cancer is an exceptional tumour entity within the variety of gastrointestinal tumours. While clinical techniques such as rectal digital examination and endoscopy would enable diagnosis as early as the stage of polypoid preneoplasia, only 10% of rectal cancer patients undergo surgery at an early stage of the disease. The prognosis of rectal cancer without infiltration of the muscu- laris is relatively good. However, with locally more advanced tu- mours, possibly associated with lymphnode metastases, the prob- ability of successful treatment decreases considerably. Further- more, there is a clear prognostic discrepancy between proximal and distal rectal cancers. Rectal carcinomas, especially in the dis- tal location, except those diagnosed at an early stage, usually re- quire surgical treatment with postoperatively disturbed or lost anal sphincter function. A permanent colostomy may not be avoidable. The current trends and developments in diagnosis and therapy of rectal cancers may be described as follows: * The search for new diagnostic procedures and the attempt to define risk groups for which intensive preventive measures would be clearly successful. New insights may come from mod- ern molecular biology or molecular genetics, especially with re- gard to hereditary colorectal carcinoma. * A further increase in the rate of sphincter-preserving surgery without impairment of local tumour control or overall prog- nosis. New surgical techniques such as trans sphincteric resec- tion, but also various multimodal local treatment regimens, especially for low-risk tumours, are promising approaches.