Background. Elevated tumor marker levels have been reported in heart failure patients with left ventricular (LV) systolic dysfunction and enlargement. The levels of several tumor markers, including CA 125, CA 19-9, CA 15-3 and CEA, in rheumatic mitral stenotic patients were compared to the control group. Materials and Methods: Tumor markers were measured in 60 mitral stenotic patients and in 30 normal subjects who served as the control group. Mitral stenotic patients were classified into two categories of cardiac dysfunction based on the classification of the New York Heart Association (NYHA). Group I consisted of 31 patients in NYHA class 3-4 and group II of 29 patients in NYHA class 1-2. Echocardiographic examinations and invasive hemodynamic monitoring were performed in all patients. Results: Group I patients had decreased mitral valve area (p = 0.004) and higher left atrial diameter (p = 0.003) than group II patients. Right atrial, mean pulmonary artery and pulmonary capillary wedge pressures and transmitral gradient were higher in group I than in group II (p = 0.010, 0.0001, 0.0001 and 0.0001, respectively). CA 125 levels were statistically higher in mitral stenotic patient groups than in the control group (p < 0.0001). No statistically significant differences were shown for the other tumor markers. Group I patients had higher CA 125 levels compared to group II (p < 0.0001). Conclusion: Elevated CA 125 levels may be due to venous congestion and activation of peritoneal mesothelium or increased signal peptides. Copyright (C) 2003 S. Karger AG, Basel.