Constipation is a common symptom affecting 2-27% of general population in Western countries. According to a population-based study on bowel habits in a Korean community, the prevalence was 16.5% for self-reported constipation and 9.2% for functional constipation. There is a broad range of causes for constipation. There are three subtypes in functional constipation, although overlap is not uncommon. Physiologic studies such as colonic transit test, anorectal manometry, balloon expulsion test, and defecography can be helpful in further evaluating and classifying functional constipation. Slow transit constipation is characterized by prolongation of transit time through- out the colon, caused by either myopathy or neuropathy. Functional defecation disorder is characterized as an inability to initiate defecation following the urge to do so, a feeling of incomplete evacuation, tenesmus, excessive straining or manual evacuation. Normal transit constipation is the most common subtype and characterized by constipation occurring in the presence of normal colonic transit time and normal defecatory function. It is important for clinicians to choose appropriate treatment for constipation which are most efficacious for the individual patient. Most patients with functional constipation respond to laxatives, but a small proportion may be resistant to this treatment. In patients with functional defecation disorder, biofeedback is helpful. Sacral nerve stimulation may be helpful in some patients with slow transit constipation. Patients who are resistant to all the conservative modalities may require surgical intervention. Extensive clinical and physiological preoperative assessment of patients with slow colonic transit time is essential before considering surgery, including an assessment of small bowel motility and identification of coexistent defecatory disorder.