Genetic epidemiological methods have played an integral role in the characterisation of the genetic susceptibilities to colorectal cancer. Classic epidemiological approaches, such as case-control and prospective cohort studies, that utilise family history information have laid the foundation for the more specialised family-based genetic methods, segregation analysis and linkage analysis. The genetic epidemiology of colorectal cancer can be characterised by several themes: the consistently increased risk of colorectal cancer in first-degree relatives of patients with colorectal cancer; genetic predisposition to some, if not the majority of colorectal neoplasms; and genetic heterogeneity of the inherited colorectal cancer syndromes. With the rapid development of molecular genetic techniques, new opportunities for further research include studies to estimate the proportion of colorectal cancer that is accounted for by genetic susceptibility, the number of loci that may be involved, and most importantly, gene-environment interaction studies, not only of the inherited syndromes, but of common colorectal cancer.