BACKGROUND: The present study aimed to assess a newly introduced, hospitalist-run, acute medical unit (AMU) model in Korea. The AMU in our institution started in October 2015. Four hospitalists managed patients with acute medical needs that were admitted through the emergency department (ED). STUDY DESIGN: We conducted a retrospective cohort study of all medical inpatients admitted through the ED from June 1, 2016 to May 31, 2017, at a tertiary care hospital. We evaluated 6391 patients whether the hospitalist care in the AMU improved patient outcomes compared to standard non-hospitalist care. METHODS: We created multivariate analysis models to compare the clinical outcomes of patients cared for by hospitalists with the outcomes of patients cared for by non-hospitalists. RESULTS: In the adjusted models, compared to the non-hospitalist group, the AMU hospitalist group had a lower in-hospital mortality (OR: 0.46, P <0.001), a lower intensive care unit (ICU) admission rate (OR: 0.39, P <0 .001), a shorter hospital length of stay (coefficient: -1.349, SE: 0.217; P <0.001), and a shorter ED waiting time (coefficient: -3.021, SE: 0.256; P <0.001). There were no significant differences in the 10-day or 30-day re-admission rates (P = 0.493, P = 0.201; respectively). CONCLUSIONS: The AMU hospitalist care model was associated with reductions in in-hospital mortality, ICU admission rate, length of hospital stay, and ED waiting time. These findings suggested that this AMU hospitalist care model might be adaptable to other healthcare systems to improve care for patients with acute medical needs.