We present a case of right ventricular myocardial infarction, secondary to postangioplasty occlusion of ventricular ramus of the right coronary artery, that developed electrocardiographic changes suggestive of septal myocardial infarction, this diagnosis was eliminated through angiographic study. We conclude that the carefully analysis of the electrocardiographic changes in ST segment in V1 to V4 can guide to the diagnosis of right ventricular myocardial infarction. For that reason we recommend the routinary register of the right electrocardiographic derivations as V3R and V4R, and left derivations V7 and V8, that is, the thoracic circle, in all patients with acute myocardial infarction regardless its location.