BACKGROUND: In the last decade our understanding of pelvic floor function and dysfunction has improved significantly. A more rational diagnostic and therapeutic approach is now possible for the group of patients with constipation due to obstructed defecation (OD). METHODS: The review is based on a literature search using the PubMed database focusing mainly on recent literature addressing the subject. RESULTS: Obstructed defecation occurs in about 7% of the adult population. Different pathophysiological mechanisms, either functional or anatomical, eventually lead to OD. Different tests (defecography, balloon evacuation test, manometry, electromyography, colonic transit time measurementmanometry) play an important role to quantify the problem. These tests are not without problems as abnormal results are also found in asymptomatic controls. Also, there is poor agreement between different tests and a poor correlation with symptomatology. Thus, for most syndromes conservative treatment including biofeedback is appropriate. Surgery can yield excellent results in selected cases. CONCLUSION: Validation of scoring systems and quantitative tests is still needed. More uniform and strict criteria for anismus should be applied to make therapeutic approaches comparable. Appropriate selection of patients for surgery is the key to success.