Accessory mitral valve is a rare congenital abnormality and is an unusual cause for subvalvular left ventricular outflow tract (LVOT) obstruction. It is detected first in children and is very rarely noticed in adults. The most common clinical presentation is symptomatic LVOT obstruction. We present a case series of 5 adult patients with varying clinical presentations in which the accessory mitral valve was diagnosed using echocardiography. Three patients presented with varying degrees of symptomatic LVOT obstruction, one presented with recurrent transient ischemic attack and stroke, and one patient was incidentally diagnosed during echocardiography to exclude endocarditis. Accessory mitral valve should be suggested in patients with LVOT obstruction.