Acute myocardial infarction (AMI) often is unrecognized (i.e., a patient fails to notice or report the event to the physician, or the physician fails to diagnose it). Psychosocial differences between patients with recognized and unrecognized AMI have not been examined. We compared 40 patients who sought treatment for a documented AMI with 30 patients who were found on routine electrocardiogram to have had an AMI for which they did not seek medical care. Patients with unrecognized AMI showed greater "alexithymia," or deficient psychologic awareness (p = 0.04; Alexithymia Provoked Response Interview), and a greater belief that chance factors determine their health (p = 0.004; Multidimensional Health Locus of Control Scale). Patients with unrecognized AMI were less likely to have angina, yet did not differ from those with recognized AMI with regard to demographics, smoking, systemic hypertension, diabetes mellitus, AMI location, depression, or hypochondriasis. We hypothesize that deficient psychologic awareness may impede AMI symptom perception or recognition, and that the belief in chance or fate as determining health may inhibit treatment-seeking.