Introduction: The Acute Physiology and Chronic Health Evaluation II (APACHE II) scoring system was developed to predict hospital mortality, which can be used as a predictor of final hospital outcome in coronavirus disease 2019 (COVID-19) patients. Therefore, the present study was designed and conducted with the aim of determining the average APACHE II score in patients with COVID-19 patients. Methods: In this cross-sectional study, patients with COVID-19 infection confirmed by PCR test were enrolled in the ICU of Imam Khomeini Hospital in Urmia city during 2020–2022. The laboratory, radiological, and clinical findings of the patients were collected and evaluated. The APACHE II scores of the patients were also calculated by the specialists of ICU and Infectious Diseases Department for each patient and recorded in the checklist. Results: A total of 150 patients were examined in this study. The mean age of the patients was 53.71±16.02 years; 82 patients, or 54.7%, were male, and 68 patients, or 45.3%, were female. The mean APACHE II score was 10.12±6.3; 105 patients (0.70%) were discharged, and 45 patients (0.30%) died. The mean APACHE II score was significantly higher in patients with cough (P=0.001), shortness of breath (P=0.002), hemoptysis (P>0.001), gastrointestinal hemorrhage (P=0.002), and renal failure (P=0.001). In addition, there was a significant direct relationship between age and APACHE II score, such that APACHE II score increased significantly with age (r=0.53, P>0.001). The mean APACHE II score in men was 10.04±5.8 and in women was 10.20±6.9, and according to the results of the independent t-test, there was no statistically significant difference between the two sexes (0.88). The mean APACHE II score was lower in patients with a history of dialysis (P=0.01), thyroid disease (P>0.001), hypertension (P>0.001), ischemic heart disease (P=0.04), and diabetes (P=0.02) were significantly higher. Conclusion: Patients with gastrointestinal bleeding, cough, shortness of breath, hemoptysis, and renal failure after COVID-19 infection, with a history of dialysis, thyroid disease, hypertension, and diabetes, and intubated patients had a significantly higher APACHE II score. A significant relationship was found between patients’ age and the APACHE II score. However, this index was not a suitable criterion for predicting death in COVID-19 patients.