In recent years molecular biology has been applied to the study of colonic carcinoma, both in the human and in the experimental animal. The data obtained have enriched our understanding of colonic carcinogenesis and are of potential interest for cancer diagnosis and prevention. In this paper we review part of the available literature on the molecular characterisation of colon tumors, with emphasis on the issues of clonality, in vitro cell lines, tumor progression and heredity of colon cancer