A 34-year-old mother developed acute myocardial infarction (MI) 10 days postpartum while taking bromocriptine for ablactation. Her only known risk factor was moderate hypercholesterolemia. The initial coronary arteriogram revealed minimal irregularities of the mid- and distal left anterior descending (LAD) artery, but severe narrowing of a large first diagonal branch of the LAD. Repeat coronary arteriography, performed two months later for recurrent chest pain, showed no significant change in the LAD. There was, however, a marked improvement in the first diagonal branch. To the authors' knowledge this is the 10th report of MI in a patient using bromocriptine postpartum for milk suppression and only the second one to implicate by its investigations the role of vasospasm in the coronary vessels at the cause of the infarction.