We report an extremely rare case of a left ventricular tumor producing carbohydrate antigen 19-9 (CA19-9). A 43-year-old man with an episode of right hemiplegia underwent an emergent operation for a left ventricular tumor just beneath the posterior leaflet of the mitral valve. The tumor was successfully resected by mobilization of the posterior leaflet of the mitral valve. The resected specimen was immunoreactive for CA19-9.