Background: Many systems are being applied to predict mortality of the patients in ICUs. In this study, the patients admitted to EICU were compared to those of MICU and SICU using APACHE-II scoring system to predict their mortality.

Methods: In this retrospective cohort study, the files of 290 patients admitted toEICU, MICU, and SICU of RasoulAkram Hospital in Tehran, were evaluated in a 6 month period. The outcome of every patient wascollected, patients’ APACHE-II scores were calculated, and the departments were compared each other.

Results: There was no statistically meaningful difference among the patients of departments evaluated for age and sex. APACHE-II scoresof patients of EICU were meaningfully lower than two other wards.The stay length and mortality rate of patients admitted to EICU were meaningfully lower than two other wards.

Conclusion: The results of this research showed that in the hospital studied, the disease severity of the patients admitted to MICU and SICU were higher than the patients of EICU. On the other hand, the patients admitted to EICU, had lower length of stay and mortality compared to the two other wards.