In an attempt to identify angiographic and clinical predictors of reperfusion, 42 patients who received intracoronary streptokinase during the early phase of myocardial infarction were analyzed. The different morphologies (regular and irregular) of the occlusive lesions did not show a significant relation with the response (reperfusion vs nonreperfusion) to intracoronary streptokinase; neither did the presence of angiographically visualized thrombus in the infarct-related artery favor reperfusion. Among the clinical variables analyzed (previous myocardial infarction, previous angina, diabetes mellitus, hypertension, use of tobacco, and hyperlipidemia), a history of previous angina was significantly related to absence of reperfusion (p = 0.001). Although the presence of thrombus showed a trend toward reperfusion (p = 0.1), overall, our angiographic observations did not contribute to predicting the response to streptokinase. Further studies are needed to identify morphologic criteria favoring reperfusion and select groups of patients most likely to benefit from it. © 1987.