Fibroma, the second most common tumor in childhood, usually is a large solitary mass involving the ventricular septum or the left and rarely the right free ventricular wall. An unusual case of a 5.2-year-old boy with a large mass originating from the pulmonary valve is reported. The patient presented for evaluation of a murmur. Echocardiography and cardiac magnetic resonance imaging showed a large tumor extending from the distal right ventricular outflow tract through the pulmonary valve and into the main pulmonary artery causing moderate obstruction. The patient had a fatal cardiac arrest while awaiting surgery. The postmortem examination proved the tumor to be a fibroma.