Background. Emergency physicians (EPs) face critical admission decisions, and their judgments are questioned in some developing systems. This study aims to define the factors affecting mortality in patients admitted to the hospital by EPs against in-service departments' decision and evaluate EPs' admission diagnosis with final discharge diagnosis. Methods. This is a retrospective analysis of prospectively collected data of ten consecutive years (2008-2017) of an emergency department of a university medical center. Adult patients (>= 18 years-old) who were admitted to the hospital by EPs against in-service departments' decision were enrolled in the study. Significant factors affecting mortality were defined by the backward logistic regression model. Results. 369 consecutive patients were studied, and 195 (52.8%) were males. The mean (SD) age was 65.5 (17.3) years. The logistic regression model showed that significant factors affecting mortality were intubation (p<0.0001), low systolic blood pressure (p=0.006), increased age (p=0.013), and having a comorbidity (p=0.024). There was no significant difference between EPs' primary admission diagnosis and patient's final primary diagnosis at the time of disposition from the admitted departments (McNemar-Bowker test, p=0.45). 96% of the primary admission diagnoses of EPs were correct. Conclusions. Intubation, low systolic blood pressure on presentation, increased age, and having a comorbidity increased the mortality. EPs admission diagnoses were highly correlated with the final diagnosis. EPs make difficult admission decisions with high accuracy, if needed.