One-hundred records taken at chance from the archives of the Instituto Nacional de Cardiología de México, with the diagnosis of healthy heart, were studied. The following factors of these patients were analyzed: age, sex, civil status, socio-economic level, occupation, family antecedents, personal antecedents, smoking, alcoholism, presence of cardiac murmurs, arrhythmias, and electrocardiogram. In 80 of these patients there existed a clear neurotic alteration. The main symptoms which they suffered were: dyspnea, pain, palpitations, dizziness, and headaches. We found that the influence of the medical environment and living with cardiac patients in a neurotic individual were predisposing factors of a cardiac neurosis. In many cases the physician is responsable if he hesitates or does not advice properly. It can be concluded that it is necessary to establish a rehabilitation program for these patients since the illness is serious and invalidating and very frecuent, with repercussions at the familiar, social, and economic levels.