The combination of abciximab with thrombolytic therapy when treating acute ST-elevation myocardial infarction has been hypothesized to enhance microvascular perfusion. Resolution of ST-segment elevation after thrombolytic therapy is believed to be a marker of myocardial reperfusion and to predict mortality rate. Among 16,588 patients enrolled in the Fifth Global Use of Strategies to Open Occluded Arteries in Acute Myocardial Infarction trial, 1,764 consecutive patients from selected centers had their study electrocardiograms evaluated by a core laboratory for ST-segment deviation resolution 60 minutes after treatment. Patients were categorized into 4 groups: complete resolution (>70%), partial resolution (<70% to 30%), no resolution (<30%), and worsening ST-segment deviation. Patients treated with reteplase or a combination of reteplase plus abciximab had similar rates of complete resolution (32% vs 34%), partial resolution (29% vs 27%), no resolution (15% vs 16%), and worsening ST-segment elevation (23 vs 23%; p = 0.59). The 30-day mortality rates in these 4 groups were 2.1%, 5.2%, 5.5%, and 8.1% (p <0.001). Even after accounting for baseline variables, incomplete ST-segment resolution (<70%) was associated with an increased risk of death within 30 days (adjusted hazard ratio 2.41, 95% confidence interval 1.25 to 4.63, p <0.008). Thus, ST-segment resolution at 60 minutes was no different in patients treated with full-dose reteplase from those treated with a combination of abciximab and reteplase. Patients with >70% ST-segment resolution within 60 minutes had markedly decreased mortality rates, irrespective of treatment.