The case of a 30-year-old man with myocardial infarction localized in the interventricular septum is described. Coronary angiography performed on day 28 after the onset of symptoms revealed ectasia in the right and left coronary arteries, but no overt stenotic or occlusive lesions were present. Spasm was induced in the first septal branch of the left anterior descending artery by an acetylcholine provocation test, and single photon emission computed tomography myocardial perfusion imaging showed a reduced thallium-201 uptake localized in the interventricular septum.