We report two cases of pregnant women who developed an acute myocardial infarction. The proposed cause of massive myocardial anterior and interventricular wall infarction of the first patient appears to be bacterial intracoronary thrombus during the course of bacterial endocarditis. Acute insufficiency of the mitral valve caused by rupture chordae tendineae of the anterior mitral left was another complication. Labor contractions occurred on the 13th day of treatment. On the next day the patient gave birth to a healthy child by elective cesarean section. She was also qualified for an operation because of increased signs of left ventricular heart failure. Preoperative coronary angiography revealed occlusion of the anterior descending branch and reconstruction of its periphery. Other vessels were not changed. The patient was subjected to implantation of artificial valve, an aortocoronary by-pass and repair of atrial septal defect. Eighteen months follow up was uneventful. The second case was a 29 year-old pregnant woman who had previously undergone mitral commissurotomy admitted because of an acute myocardial infarction in the II trimester. No complication of the disease was observed.