Antimyocardium antibodies (AMA) have been observed in patients with acute myocardial infarction (AMI). At present it is unknown if these AMA play a role in the pathogenesis of acute or chronic myocardial damage or if they are only produced as a result of tissue destruction, disappearing later without clinical manifestations. However, some studies have shown that patients with AMI and AMA have higher possibilities of presenting heart failure and death. The aim of the present study was to determine if there is an association (odds ratio, OR) between AMA and death in patients with AMI. The design was a cross-sectional study. One hundred patients with acute myocardial infarction were recruited consecutively at the Coronary Care Unit of the Hospital de Especialidades at La Raza National Medical Center, IMSS, Mexico City. IgG antimyocardium antibodies were identified using the enzyme-linked immunosorbent assay technique (ELISA). Of the 100 patients studied, 81 were males and 19 females, with an average age of 58 +/- 11 years. Of the population studied, 44% showed AMA. It was observed that patients with positive AMA had an OR for heart failure of 3.40 (CI 95% 0.97-12.5, p = 0.06) and for death of 7.94 (CI 95%, 1.49-56.1, p = 0.003). This variable was analyzed with other confounding variables using logistic regression, and an OR of 11.8 (CI 95% 1.63-86.3, p = 0.001) was obtained. AMAs were an independent predictive factor for mortality in patients with AMI.