Constipation is a symptom but can generally be defined as less than three bowel movements per week. The history and physical examination should be evaluated for stool size, frequency, and straining and discomfort on defecation. The influence of age, gender, and society should also be considered. The etiologies of constipation can be classified as 1. dietary; 2. drug induced; 3. metabolic; 4. neurologic; or 5. anatomic. If hard or small stools are part of the initial evaluation, then a dietary approach of increased dietary fiber intake can be used as a therapeutic trial. If it does not succeed or the history and physical evaluation indicate an etiology other than dietary, then barium-contrast enema, flexible sigmoidoscopy, colonoscopy, transit time, or anorectal manometry can be used selectively in further evaluation. Detailed methods of treatment are described, such as how to increase fiber intake by use of dietary history and recommendation of appropriate fiber, food, or supplement intake. Methods of using behavioral changes such as laxation and toilet-training programs are described. In selected situations pharmacologic therapy and, rarely, surgical intervention, can be useful.