This serial follow-up study was designed to identify the time course of reocclusion and/or restenosis after direct angioplasty for acute myocardial infarction. Direct angioplasty for acute myocardial infarction was attempted in 160 patients. Of the 141 patients who underwent successful reperfusion and were discharged, 137 (97%) were enrolled in this study. At the 3-week follow-up study (100% eligible), angiographic restenosis of the infarct-related artery was documented in 21 patients (16%), 9 (43%) of which were reocclusions. At 4 months in 100 patients (92% of those eligible), restenosis was newly documented in 28 infarct-related arteries (28%), 3 of which were reocclusions (11%). At 1 year in 64 patient (89% of those eligible), restenosis was newly documented in 5 infarct-related arteries (7.8%), with no reocclusions. The cumulative restenosis rate was 20% at 3 weeks, 43% at 4 months, and 47% at 1 year; when divided into occlusive and nonocclusive types, restenosis rates were 12% and 8.8% at 3 weeks and 14% and 29% at 4 months, respectively. Restenosis was most prevalent within the first 4 months and rarely occurred after that. When restenosis is manifested as reocclusion, it occurs earlier than in nonocclusive restenosis, often within 3 weeks.