Antiphospholipid syndrome is a systemic autoimmune syndrome with cardiac manifestations such as nonbacterial thrombotic endocarditis, also known as Libman-Sacks endocarditis. A 61-year-old female with history of antiphospholipid syndrome presented in acute pulmonary edema. Echocardiography demonstrated mobile vegetations on the free margins of both the anterior and the posterior mitral valve leaflets. Blood cultures and fungal serologies were negative. During mitral valve replacement both the anterior and posterior mitral leaflets were covered with multiple small vegetations with features of nonbacterial thrombotic endocarditis. Though mostly asymptomatic, Libman-Sacks endocarditis may be an indication for valve replacement.