To compare in-hospital outcomes between left ventricular myocardial infarction (LVMI) patients with and without right ventricular myocardial infarction (RVMI). Patients with acute ST-segment elevation MI (STEMI) undergoing primary percutaneous coronary intervention (PCI) were enrolled and divided into LVMI with and without RVMI groups. Between-group differences and in-hospital outcomes were compared. Compared to patients without RVMI, patients with RVMI were more likely to be male, have higher body mass index, serum levels of C-reactive protein (8.9 +/- 2.4 vs 6.2 +/- 2.1 mg/dL), B-type natriuretic peptide (1295 +/- 340 vs 872 +/- 166 pg/mL) and cardiac troponin-I (8.6 +/- 2.9 vs 5.2 +/- 2.1 ng/mL), and have diabetes (36.3% vs 3.4%) and dyslipidemia (53.4% vs 48.1%). Patients with RVMI had lower left and right ventricular ejection fraction (50.5 +/- 5.6% vs 53.4 +/- 3.8% and 33.6 +/- 2.9% vs 45.7 +/- 2.0%), but had higher mean pulmonary artery pressure (30.6 +/- 3.3 vs 23.8 +/- 3.1 mm Hg). Compared to patients without RVMI, patients with RVMI had higher odds of in-hospital allcause mortality (4.1% vs 1.0%) and new onset acute heart failure (3.4% vs 1.0%). After adjusted for confounding factors, LVMI with RVMI remained independently associated with composite outcomes, with odds ratio 1.66 (95% confidence interval 1.39-2.04). Compared to isolated LVMI patients, those with concomitant RVMI have higher odds of in-hospital complications, particularly all-cause mortality and new onset acute heart failure.