Patients affected with one of the syndromes of hereditary colorectal cancer are at a higher than average risk of developing a colorectal cancer, or a cancer in another organ. The spectrum of organs at risk varies with the syndrome. In most syndromes, there is a range of risk due to different genotypes, and differences in phenotype even in patients with the same genotype. Gender is an obvious factor in influencing cancer risk and the organs potentially involved, but other factors such as ethnicity and environment may also operate. This chapter discusses the management of affected patients in broad terms to give perspective to the choice of treatments and the timing of care.