Accessory mitral valve tissue is a rare congenital malformation, which often causes left ventricular outflow tract (LVOT) obstruction. Patients with accessory MVT and LVOT obstruction have poor exercise tolerance, fatigue, palpitations. The disease is mainly diagnosed in the 1 st decade of life, when symptoms occur. Rarely diagnosis is made later, after 20-30 years of life, due to progressive course of the pathology with increasing gradient of LVOT obstruction. In cases of severe LVOT obstruction surgical management is recommended. We report a case of AMVT in young man diagnosed at the age of 31, when LVOT obstruction occurred and exercise intolerance developed.