The benefit of primary percutaneous coronary intervention is limited by a 5% to 20% incidence of suboptimal epicardial coronary blood (< or = TIMI-2 flow). Recently, data has demonstrated that when administered in conjunction with primary stenting for the treatment of acute myocardial infarction (AMI), abciximab improves the success rate of the stenting procedure and provides additional clinical benefits. But data on a combination of tirofiban and primary stenting for treatment of ST-segment elevated (ST-se) AMI is unknown. Between May 1999 and September 2000, primary stenting without adjunctive tirofiban therapy was performed in 136 consecutive patients (control group) with ST-se AMI. Between January 2001 and May 2002, we routinely administered tirofiban to 133 consecutive patients (study group) with ST-se AMI before they underwent primary stenting. The angiographic and clinical outcomes of both groups were compared in a chronologically consecutive manner. The overall mortality rate was significantly higher in patients with failed (< or = TIMI-2 flow) than in patients with successful (TIMI-3) reperfusion (20.0% vs 3.5%, P < 0.0001). Univariate analysis demonstrated that there were no significant differences in the successful reperfusion (85.7% vs 84.6%, P = 0.84) or 30-day combined end points - death, recurrent ischemia or reinfarction (8.3% vs 11.0%, P = 0.59) between study and control group patients. Clinical variables were used to statistically analyze potential risk factors for unsuccessful reperfusion (< or = TIMI-2 flow) in the study group patients. Multiple stepwise logistic regression analysis demonstrated that the reference lumen diameter (RLD) of the infarct-related artery (IRA) > or = 3.5 mm (P = 0.0004) and the lesion length of the obstruction > or = 20.0 mm (P = 0.018) were the significant independent predictors of failed normalized coronary blood flow. There were no significant differences in the restenotic rate of IRA (29.2% vs 30.8%, P = 0.9) or mortality rate (1.6% vs 1.6%, P = 1.0) at six-month follow-up. In conclusion, our study demonstrates that primary stenting with adjunctive tirofiban therapy in ST-se AMI did not provide additional benefits in short-term and intermediate-term angiographic and clinical outcomes compared to conventional primary stenting.