OBJECTIVE: This study aimed to determine the correlation between selected electrocardiogram (ECG) parameters (recorded at admission) and mortality in non-cardiac, non-COVID-19 intensive care unit (ICU) patients, and to determine the sensitivity and specificity of a novel admission ECG score (AD-ECG) for predicting mortality. Additionally, the sensitivity and specificity of the AD-ECG and Acute Physiology and Chronic Health Evaluation II (APACHE II) scores for predicting ICU mortality were compared. PATIENTS AND METHODS: Clinical and laboratory data, and ECG parameters were compared between ICU survivors and non-survivors. ECG parameters (the QTc and Tpe intervals, and the Tpe/QT and Tpe/QTc ratios) and pulse pressure at ICU admission (baseline) were used to calculate the AD-ECG score. Cut-off values for ECG parameters, pulse pressure, and AD-ECG and APACHE II scores were calculated. The sensitivity and specificity of the APACHE II and AD-ECG scores were determined. RESULTS: The study included 167 patients. Mortality was higher in the patients with comorbidities, mechanical ventilation, and length of ICU stay (p < 0.05). The QTc and Tpe intervals, and the TPe/QT and TPe/QTc ratios differed significantly between the survivors and non-survivors (p < 0.05). The sensitivity and specificity of the AD-ECG score were similar to those of the APACHE II score. When pulse pressure, and the QTc and Tpe intervals were added to APACHE II, the sensitivity of the APACHE II score increased from 78.9% to 85.5%, and its specificity increased from 75% to 86.8%. CONCLUSIONS: A novel admission ECG score (AD-ECG) based on ECG parameters (the QTc and Tpe intervals, and the Tpe/QT and Tpe/QTc ratios) and pulse pressure has similar sensitivity and specificity as the APACHE II score for predicting non-cardiac ICU mortality. Adding pulse pressure, and the QTc and Tpe intervals increases the sensitivity and specificity of the APACHE II score; however, as the present study included non-cardiac patients only, additional larger-scale studies are needed to obtain more precise results.