Several markers of colon cancer have been described in humans. The study of polyp recurrence is a reliable procedure, but long and expensive. Mucosal cell proliferation is increased in high-risk subjects, often with a displacement of proliferation toward the lumen. Increased apoptosis in colon crypts is associated with protection against experimental cancer, but the method is not validated for humans. Aberrant crypt foci (ACF) can be scored in humans in resected specimens or visualized endoscopically. ACF and colon cancer risk seem connected in Japan, but not in Europe or North America. In conclusion, assessment of individuals or populations at risk of colon cancer still relies on a combination of different methods.