Objective Prompt reperfusion is important for patients with ST elevation myocardial infarction (STEMI). However, patients often require interhospital transfer for percutaneous coronary intervention (PCI) because not all hospitals can provide. The purpose of this study is to reduce the PCI delay using a regionalization protocol in patients with STEMI following transfer from another hospital lacking PCI facility. Methods We established a revascularization protocol designated as Preparing Revascularization Effort before Patients' Arrival via Regionalization Engagement (PREPARE) for the STEMI patients transferred from an outside regional hospital. The protocol included immediate referral acceptance by an emergency physician, real-time electrocardiogram sharing via mobile phone and early activation of the PCI team. We analyzed the differences between the PREPARE and the non-PREPARE groups. Results In the PREPARE group, the median time from the first hospital visit to the ballooning procedure via PCI at the receiving facility (D1-to-B time) was 111.0 (interquartile range 97.0-130.0) minutes, which was significantly shorter than in the non-PREPARE group 134.0 (interquartile range 115.0-182.0) minutes. The proportion of D1-to-B time within 120 minutes was 30.4% in the group and 60.0% in the PREPARE group, which represents a significant difference (P = 0.004). Multivariate logistic regression analysis revealed that patient transfer via PREPARE protocol (odds ratio, 3.399; 95% confidence interval, 1.150-10.050, P = 0.027) was related to adequate D1-to-B time. No statistically significant differences were found in the hospital length of stay or major adverse cardiac events within 4 weeks. Conclusion The PREPARE protocol is an effective strategy to reduce the time to revascularization of the transferred STEMI patients.