Organophosphorus (OP) insecticides are one of the most important pesticides, and poisoning induced by them is a major global health problem with about 3 million intoxications and 300,000 deaths occurring worldwide every year. This study aimed to investigate the relevance of ECG findings and prognostic value of corrected QT (QTc) interval in acute OP poisoning cases. The study recruited 91 patients suffering from acute OP poisoning, who were admitted to Tanta University Poison Control Center over a period of two years (March 2013 – March 2015). ECG changes, QTc interval length, and the different outcomes of the patients were recorded including mortality, the need for endotracheal intubation and/or mechanical ventilation, the length of hospital stay, and the total amount of atropine and/or obidoxime administered. The higher need for intubation and assisted ventilation in patients with prolonged QTc compared to patients with normal QTc was statistically significant. The mortality rate in the long QTc group was not significantly different from that of the normal QTc group. Moreover, there was no statistically significant difference between the two groups regarding the length of hospital stay or the doses of obidoxime and atropine required to control the muscarinic signs and symptoms. However, the total atropine dose was significantly lower in survivors than non survivors. It could be concluded that QTc interval prolongation needs to be considered as a prognostic indicator in acute OP poisoning.