A 42-year-old woman with no known risk factors had an acute myocardial infarction at 32 weeks' gestation and went into premature labor. She required invasive hemodynamic monitoring and inotropic support. Congestive heart failure improved dramatically after cesarean section. During the acute infarction, ventricular dysfunction was out of proportion to the ultimate ventricular damage. The concept of the stunned myocardium is used to explain this finding and to justify early cesarean section. Another complication of her infarction, left ventricular thrombosis, has not previously been described in pregnancy.