We aimed to evaluate the efficacy of QT dispersion (QTD) in determining the outcome of the patients poisoned by cardiotoxic medications and toxins. Patients who referred to our emergency department (ED) due to acute toxicity with any cardiotoxic medication or toxin and were admitted to medical toxicology intensive care unit (MTICU) were enrolled into the study. A questionnaire containing the demographic characteristics, vital signs, laboratory tests, electrocardiographic (ECG) parameters of the first ECG taken on MTICU or ED admission, simplified acute physiology score (SAPS), and acute physiology and chronic health evaluation (APACHE) score was filled for every single patient. QTD was manually calculated. The patients were divided into two groups of survivors and non-survivors and compared. Although QTD was not significantly different between the survivors and non-survivors (P = 0.8), SAPS II and APACHE II score were so. SAPS and APACHE had the highest sensitivity and specificity in determining the patients' mortality, respectively. SAPS had the highest sensitivity, and QTD had the highest specificity in predicting the later development of the complications. SAPS II and APACHE II scoring systems are the best systems for prognostication of death in patients with acute cardiotoxic medication-induced poisonings. QTD can be successfully used for the prediction of complications.