A survey is presented on the incidence of colorectal carcinomas in the GDR, exogenous causes possibly being responsible for the increase in incidence, common screening methods, macro-anatomy and micro-anatomy of colorectal carcinoma, staging, prognosis, and pathways of metastases. The correlation between intestinal polypi and colorectal carcinoma as well as the frequency of their degeneration are also referred to. Adenomatous polypi (polypous adenoma), villous polypi (villous adenoma), and certain rare intestinal polypi, such as familial polyposis coli, multiple polyposis of the entire gastro-intestinal tract, as well as the Gardner- and Turcot-syndromes, are some of those polypi which depending on their size tend to malignant degeneration. Histological information provided by the pathologist is discussed in its value and importance for surgical practice.