BACKGROUNDS: Patients with prior stroke represent a substantial proportion of acute ST-segment elevation myocardial infarction (STEMI). Previous studies showed that prior stroke patients who present with STEMI are high risk for short-term morbidity and mortality in the reperfusion era. However, it is not clear whether a difference in in-hospital mortality between patients with and without prior stroke exists in the primary percutaneous coronary intervention (PCI) era. So, the aim of the present study was to investigate the impact of prior stroke on hospital mortality in patients with STEMI who underwent primary PCI. METHODS: We evaluated 5770 eligible patients from the Korea Acute Myocardial Infarction Registry (KAMIR) who underwent primary PCI within 24 hours of symptom onset. Baseline characteristics and in-hospital outcomes were analyzed. RESULTS: 322 (5.6%) had prior stroke (68.6% men, 68.0짹10.6 years) and 5448 (94.4%) had not (62.1짹12.8 years). Patients with prior stroke were more likely to have history of hypertension (71.3% vs. 44.9%), diabetes (35.6% vs. 23.8%), and congestive heart failure (2.5% vs. 1.0%). Also, Killip class���2, atrial fibrillation at admission and multivessel disease were more frequent in patients with prior stroke (p<0.05). Compared to patients without prior stroke, in-hospital new onset atrial fibrillation (3.4% vs. 1.3%), cardiogenic shock (12.4% vs 6.1%), cerebrovascular event (2.2% vs. 0.6%), major bleeding (1.6% vs. 0.4%) rates were significantly higher in patients with prior stroke (p<0.05). On multivariable analysis, prior stroke was an independently associated with in-hospital mortality (odds ratio 1.98, p=0.028). CONCLUSIONS: Patients with prior stroke who present with STEMI are still at high risk for in-hospital adverse outcomes and mortality in primary PCI era. Meticulous management for these patients appears warranted.