ObjectiveTo assess a newly introduced, hospitalist-run, acute medical unit (AMU) care model at a tertiary care hospital in the Republic of Korea.DesignRetrospective cohort study.SettingTertiary care hospital in the Republic of Korea.ParticipantsWe evaluated 6391 medical inpatients admitted through the emergency department (ED) from 1 June 2016 to 31 May 2017.InterventionsThe study compared multiple outcomes among medical inpatients from the ED between the non-hospitalist group and the AMU hospitalist group.Outcome measuresIn-hospital mortality (IHM), intensive care unit (ICU) admission rate, hospital length of stay (LOS), ED-LOS and unscheduled readmission rates were defined as patient outcomes and compared between the two groups.ResultsCompared with the non-hospitalist group, the AMU hospitalist group had lower IHM (OR: 0.43, p<0.001), a lower ICU admission rate (OR: 0.72, p=0.013), a shorter LOS (coefficient: −0.984, SE: 0.318; p=0.002) and a shorter ED-LOS (coefficient: −3.021, SE: 0.256; p<0.001). There were no significant differences in the 10-day or 30-day readmission rates (p=0.974, p=0.965, respectively).ConclusionsThe AMU hospitalist care model was associated with reductions in IHM, ICU admission rate, LOS and ED-LOS. These findings suggest that the AMU hospitalist care model has the potential to be adopted into other healthcare systems to improve care for patients with acute medical needs.