Background Primary percutaneous coronary intervention (PCI) has been clearly identified as the first therapeutic option for patients with acute ST-segment elevation myocardial infarction (STEMI). The importance of reducing door-to-balloon (D2B) time has gained increased recognition. This study aimed to assess the feasibility, safety and efficacy of the strategy of direct ambulance transportation of patients with acute STEMI to catheterization lab to receive primary PCI.Methods The study population included 141 consecutive patients with chest pain and ST-segment elevation who were admitted to the catheterization laboratory directly by the ambulance and underwent primary PCI (DIRECT group).Another 145 patients with STEMI randomly selected from the PCI database, were served as control group (conventional group); they were transported to catheterization laboratory from emergency room (ER). The primary endpoint of D2B time,and secondary endpoint of in-hospital and 30-day major adverse cardiac events (MACE, including death, non-fatal reinfarction, and target vessel revascularization) were compared.Results Baseline and procedural characteristics between the two groups were comparable, except more patients in the DIRECT group presented TIMI 0-1 flow in culprit vessel at initial angiogram (80.1% and 73.8%, P=0.04). Comparing to conventional group, the primary endpoint of D2B time was reduced ((54±18) minutes and (112±55) minutes, P ＜0.0001)and the percentage of patients with D2B ＜90 minutes was increased in the DIRECT group (96.9% and 27.0%, P＜0.0001).The success rate of primary PCI with stent implantation with final Thrombolysis in Myocardial Infarction (TIMI) 3 flow was significantly higher in the DIRECT group (93.8% and 85.2%, P=0.03). Although no significant difference was found at 30-day MACE free survival rate between the two groups (95.0% and 89.0%, P=0.06), a trend in improving survival status in the DIRECT group was demonstrated by Kaplan-Meier analysis.Conclusion Direct ambulance transport of STEMI patients to the catheterization laboratory could significantly reduce D2B time and improve success rate of primary PCI and 30-day clinical outcomes.