Background: We have reported that a marked elevation in serum C-reactive protein (CRP) level is a predictor for infarct expansion and cardiac rupture after AMI. Although beta-blockers prevent cardiac rupture after AMI, their effect on serum CRP elevation has not been determined. Methods: We studied a total of 154 patients with first Q-wave AMI. Patients complicated by pump failure were excluded from this study. Eighty-two patients received P-blocker treatment within 24 h of the onset of AMI, while 72 patients received no P-blocker treatment. Peak serum creatine kinase (CK) and CRP levels were determined by serial measurements. Results: There was no difference between the groups according to age, sex, coronary risk factors, pre-infarction angina, infarct site, prior use of cardiovascular drugs, use of revascularization therapy, and prevalence of multivessel disease. beta-Blocker treatment was associated with a lower peak CRP level (6.9+/-6.1 vs. 10.8+/-9.3 mg/dl, p=0.002), a shorter duration from the onset to the peak CRP level (2+/-1 vs. 3+/-2 days, p<0.0001), a lower incidence of cardiac rupture (p=0.03) and lower in-hospital cardiac mortality (p=0.02), despite similar peak CK levels. Conclusion: The early use of beta-blockers is associated with decreased serum CRP level and a favorable clinical outcome after first Q-wave AMI, suggesting some beneficial effects of beta-blockers on infarct healing after AMI.