Although commonly detected by transthoracic echocardiography, tricuspid regurgitation (TR) has been somehow neglected, and recent data have emerged on the need for careful examination of the tricuspid valve. Functional or secondary TR is the most frequent etiology of tricuspid valve pathology in western countries and is related to tricuspid annular dilation and leaflet tethering. The prognostic role of TR associated with organic left-sided valvular heart disease is well known. However, the value of functional TR in outcome stratification of patients with advanced left ventricular dysfunction is less clear. Surgical tricuspid repair has been avoided for years, because of the misconception that TR should disappear once the primary left-sided problem is treated; this results in a large number of untreated patients with functional TR. Over the past few years, many investigators have reported evidence in favor of a more aggressive surgical approach to functional TR. Consequently, interest has been growing in the pathophysiology and treatment of functional TR. The purpose of this article is to provide a comprehensive review of TR incorporating a description of valve anatomy, etiological factors, pathophysiology, epidemiological data, natural history, clinical evaluation, along with a discussion of the important role in prognostic stratification and a summary of management guidelines.