Chronic constipation is caused by disordered colonic motility, impaired rectal evacuation (dyschezia) or a combination of the two. It is important to distinguish the predominant mechanism of constipation in order to choose the optimal therapy (laxatives or prokinetics versus pelvic floor retraining or surgery). The contribution of dyschezia to constipation can usually be identified by a digital rectal examination, but should, in our opinion, be confirmed by anal manometry, transrectal ultrasonography or defecography. These diagnostic methods provide additional information on the severity of the rectal outlet obstruction, the contribution of rectal hyposensitivity and the presence of potentially correctable anomalies such as a rectocele, enterocele or rectoanal intussusception. We conclude that clinical anorectal examination and functional studies are both necessary and complementary to each other in the evaluation and management of patients with chronic constipation who do not respond to standard laxative treatment.