Introduction and objectives: Ischemic heart disease is among the first causes of disability and death in the world. The acute myocardial infarction alters considerably the myocardial relaxation. The echocardiogram is a useful, economic and harmless method to assess diastolic function in these patients; that is why the aim of the study was to characterize the behavior of this left ventricular function by means of an echocardiography. Methods: an observational descriptive study was carried out with 91 patients with myocardial infarction who were hospitalized at the Cardiology Ward of the Arnaldo Milian Castro Provincial University Hospital in Santa Clara during 2008. An echocardiogram was performed between the fifth and the seventh day of evolution, and the patterns of diastolic function were compared with other variables. Results: There was a prevalence of the male sex (74,7 %), the infarctions without ST segment elevation were more frequent (83,1 %) – which showed a bigger alteration of the relaxation, much more when the anterior and lateral walls of the left ventricle were involved. The presence of complications was linked to a bigger alteration of the relaxation, and the most associate ones were the contractile dysfunction and malignant arrhythmias. The decrease of the ejection fraction was linked to (p = 0,000) the prolongation of the relaxation. Conclusions: There was a prevalence of the infarction without ST segment elevation. It was more frequent in the male sex and it was associated with a higher level of alteration of the relaxation. The infarctions with anterior or lateral location, and those which caused complications, presented a higher level of this alteration. All patients with a reduced ejection fraction had relaxation disorders