Double-orifice mitral valve (DOMV) is a rare anomaly commonly associated with other congenital heart diseases. We present two patients with DOMV and noncompaction of the left ventricular myocardium (NLVM). Case 1 was a 5-year-old male diagnosed with dilated cardiomyopathy. His echocardiogram showed thin myocardium with dilatation at the basal of the left ventricle, thick noncompacted myocardium around the apex of the left ventricle, and DOMV (complete bridge type) with mild mitral regurgitation. Case 2 was an 11-year-old male diagnosed with complete atrioventricular block. His echocardiogram showed thick noncompacted myocardium with mild hypokinesis from the posterior to lateral wall and DOMV (complete bridge type) with mild mitral regurgitation. DOMV is commonly associated with congenital anomaly and always has an abnormal subvalvar apparatus. The mitral valve and its apparatus embryologically originate from the endomyocardium, which is thought to be the origin of noncompacted myocardium. We speculate that patients with DOMV may have NLVM.