In the present study, the epidemiology of constipation in the United States and an assessment of its impact on national health are presented. This analysis was based on four different surveys, i.e., the National Health Interview Survey, the National Hospital Discharge Survey, the National Ambulatory Medical Care Survey, and the Vital Statistics of the United States. These surveys have estimated that over 4 million people in the United States have frequent constipation, corresponding to a prevalence of about 2 percent. Constipation was the most common digestive complaint in the United States, outnumbering all other chronic digestive conditions. Cathartics and laxatives were prescribed to 2 to 3 million patients yearly by general and family practitioners or internists. In 92,000 annual hospitalizations, constipation was listed among the discharge diagnoses. About 900 persons die annually from diseases associated with or related to constipation. Constipation was three times more common in women than men. It showed a marked increase after the age of 65 years. It appeared to affect nonwhites 1.3 times more frequently than whites. In addition, constipation was more frequent in people living in the South than elsewhere in the United States, and in people from families with low income or brief education of the head of family than in people from families with high income or a high educational level of their family head. These data suggest that there are other factors involved in the cause of constipation in addition to dietary fiber content and psychogenic infljences. The frequent occurrence of constipation and its impact on public health stress the need for further studies devoted to the epidemiology and basic pathophysiology of this condition.