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BACKGROUND Seizure and electrocardiographic (ECG) abnormalities are of the most common complications of tramadol toxicity. OBJECTIVE This study aimed to show the prevalence and predictive value of various factors for ECG findings in patients with tramadol-induced seizures. METHOD In a descriptive cross-sectional study, 146 patients with tramadol-induced seizures referred to Poursina Hospital, Guilan, Iran, between June and November 2018 were enrolled. The clinical manifestations, such as blood pressure, respiratory rate, and pulse rate (PR), and ECG parameters, including PR interval, QRS duration, R wave in aVR lead, and corrected QT interval, were assessed. Appropriate statistical tests were used to analyze the data. RESULTS We showed that tramadol dose was significantly higher in patients with abnormal ECG findings compared with those with normal ECG pattern both upon admission (p = 0.001) and after 6 hours of admission (p = 0.001). The results found the predictive value of tramadol dose for abnormal ECG patterns upon admission (odds ratio (OR) 1.014, 95 percent CI 1.008 to 1.020) and 6 hours later (OR 1.008, 95 percent CI 1.003 to 1.013) in these patients. In addition, it was revealed that PR was a strong predictor of abnormal ECG findings in patients with tramadol-induced seizures upon admission (OR 1.085, 95 percent CI 1.038 to 1.134). Nevertheless, age only predicted abnormal findings 6 hours later (OR 1.104, 95 percent CI 1.019 to 1.195). CONCLUSION Tramadol dose, age, PR, and seizures frequency could be used as indicators of abnormal ECG findings in patients with tramadol-induced seizures. KEY POINTS The results of our study showed a high prevalence of sinus tachycardia, terminal S and R waves in aVR lead terminal S wave, and the combination of these abnormalities in this subset of patients.