Tricuspid regurgitation is an incomplete closure of the tricuspid valve that causes blood to flow from the right ventricle to the right atrium when the heart contracts. The tricuspid valve is a three-piece valve between the right atrium and the right ventricle of the heart that prevents blood from the right ventricle from flowing back into the right atrium. Tricuspid regurgitation may be a primary valve disease or secondary annular dilatation due to pulmonary hypertension. Secondary tricuspid regurgitation is seen in any condition associated with elevated pulmonary artery pressure, which is the primary cause of tricuspid regurgitation. Generally, a systolic right ventricular systolic pressure of more than 55 mm Hg can lead to functional tricuspid insufficiency. The most common secondary causes are left heart failure, mitral regurgitation, mitral stenosis, primary lung disease, and primary pulmonary hypertension. Rare causes of primary tricuspid regurgitation include rheumatic heart disease, mucinous tumors, infectious or consumptive endocarditis, carcinoid heart disease, endocardial myocardial biopsy, or medical injury from pacemaker or defibrillator electrodes, and trauma. Tricuspid regurgitation should be treated by prompt medical attention to identify the cause.