49 cases of myocardial infarction during pregnancy are reviewed from the literature, considering the frequency, pathogenesis, clinical findings, prognosis, treatment, obstetrical conduct including whether abortion is indicated, and finally 17 cases of pregnancy in women with previous heart attacks are summarized. A myocardial infarction is rare, about .01-.075%, more frequent in late pregnancy or the postpartum, and in older women. This series averaged 32.9 years. 88% were due to atherosclerosis. Other risk factors were usually not reported systematically. 56% of the incidents were the 1st heart attack; 44% were preceded by angina; 68% were anterior. Pregnancy affects the EKG and white blood count, but serum enzymes are the same as in nonpregnant women. 29% of these women died, 23 went to term, and 7 gave birth prematurely. 13 labors were spontaneous, 7 required forceps, and 10 were Caesarean births. Fetal loss was 27%. Treatment is the same as that in any heart attack patient, except for lignocaine and use of anticoagulants. Abortion is only necessary in cardiac insufficiency. Delivery should probably involve forceps, epidural anesthesia, and anticoagulatns immediately after delivery, but oxytocin should be avoided. The 17 cases of pregnancy after a heart attack resulted in 1 abortion, 15 term deliveries, 3 new infarctions, and 1 death due to antoher heart attack at term.