In this study, most of the ECG changes described were non-specific to the heat stroke group. The significant increase in heart rate is attributed to the higher core temperature in the heat stroke and heat exhaustion groups. The relative bradycardia in some patients could be related to increased intracranial pressure. The shorter QT interval in G1 and G2 can be explained by the significantly higher rate in those two groups. Some of the ST-T changes in G1, as discussed, were explained by the echocardiographic findings of underlying cardiovascular abnormalities.