Angiographic studies in the acute stage of myocardial infarction have shown complete occlusion in 75-85 percent and subtotal lesions in the remaining cases. Evidence for spasm in acutely occluded arteries has been reported. However, the majority of pathological as well as intraoperative examinations have yielded thrombotic material at the site of complete obstruction. Indirect evidence of thrombotic material was provided by successful intracoronary thrombolysis in 80 percent of infarct patients with complete obstruction. There could be causative relationships between spasm, intimal damage and coronary thrombosis. Selective applications of spasmolytic and/or thrombolytic substances into occluded vessels enabled high local concentrations with doses that caused little or no systemic effect. Angiographic verification of the results of this pharmacotherapy would help to clarify the role of spasm and thrombus in the pathogenesis of the acute coronary occlusion.