Serum carbohydrate antigen (CA-125) and carcinoembryonic antigen (CEA) have always been of clinical importance in the diagnosis and follow-up of various tumors. This study was devised to investigate the relationship between these tumor markers and acute myocardial infarction (MI). Seventy consecutive cases (59 male patients with a diagnosis of acute ST segment elevation MI and 11 male patients with a diagnosis of non-ST segment elevation MI; mean age, 57+/-8.2 y) were admitted to the University Medical Center and were included in this study as "the patient group." All patients in the patient group underwent transthoracic echocardiographic examination on the third day of hospitalization. On the basis of echocardiographic findings, these 70 patients were grouped according to left ventricular ejection fraction (EF) values; EF <55% (group 1) (n=40) and EF >or=55% (group 2) (n=30). Other parameters, including systolic pulmonary artery pressure (sPAP) and mean pulmonary artery pressure (mPAP), were also measured on transthoracic echocardiography. Serial blood samples (for follow-up of myocardial enzymes (eg, creatine kinase MB [CKMB], troponin I [TnI], troponin T, and other routine parameters) were drawn from each patient. Serum concentrations of CEA and CA-125 measured at the 72nd hour of hospitalization and peak serum concentrations of CKMB and TnI in the patient group were collected for comparison between subgroups (groups 1 and 2) and with "the control group," which included 30 subjects (mean age, 54+/-7.6 y) with no history or evidence of overt cardiac disease and with normal echocardiographic findings. The presence of any condition characterized by potential elevations in CA-125, CEA, and myocardial enzymes (CKMB, TnI) was considered an exclusion criterion. Patients included in patient groups 1 and 2 differed significantly in terms of mean EF, mean sPAP, mean mPAP, and mean CA-125 values (P<.001 for CA-125; P<.05 for the other values). EF was found to be negatively correlated with sPAP (r=-0.692, P=.000) and mPAP (r=-0.393, P=.001). EF was also negatively correlated with CA-125 (r=-0.557, P=.000). A positive correlation was noted between CA-125 and sPAP (r=0.396, P=.001) and between CA-125 and mPAP (r=0.754, P=.000). A statistically significant difference was identified between the patient and control groups with regard to values for EF, PAP, CA-125, and myocardial enzymes (CKMB and TnI) (P<.05 for mPAP; P<.001 for the other values). The serum concentration of CA-125, but not of CEA, may be elevated in those with acute MI compared with normal subjects. Regardless of the presence of pulmonary hypertension, elevations in CA-125 during myocardial infarction were significantly correlated with the severity of left ventricular systolic dysfunction on transthoracic echocardiography.