Colorectal cancer is the second leading cause of death from malignancies in Western Countries. In spite of advances in treatment, little change in survival has been accomplished in last decades and this mandates greater importance to prevention and early detection. Although dietary factors have received primary attention familial clustering suggests that susceptibility to KCR is inherited. Hereditary colorectal cancer can arise on Familial Adenomatous Polyposis (HCC) or not on polyposis (HNPCC) and members of these families are at high risk of such neoplasias. Anyway, even in "sporadic" forms of KCR first-degree relatives have a 2 to 3-fold increased risk of the same cancer. The most desirable screening protocol would be a simple procedure involving only a blood test to identify gene defect by molecular biology techniques. Unfortunately, this is not practically possible, for lack of specific genetic alterations, out of FAP, and only the study of family history can enable targeted surveillance and cost-effective management strategies.