The role of dietary fiber in colon cancer is still not clear. Ecological studies suggested a protective role for high fiber intake, but more recent analysis shows similar intakes of dietary fiber in populations with high or low incidence of colon cancer. Case-control studies generally do not support a protective role for fiber. The data suggest that the effects of fiber must be considered in the context of the total diet and interactions of dietary components. A role for levels of energy intake is not excluded.