Subarachnoid haemorrhage (SAH) is a neurological emergency with high mortality rates. It is mainly caused by rupture of an aneurysm (congenital/infectious/traumatic) or rupture of an arteriovenous malformation. Electrocardiograms (ECGs) done in patients with SAH have shown morphological changes as well as arrhythmias. Subarachnoid haemorrhage (SAH) patients have often been misdiagnosed to have cardiac abnormalities based on their ECGs when in many of those instances the ECG change had been the result of the SAH itself. They have led to unnecessary and wasteful investigations and therapies in many occasions. Hence the current article is an effort at consolidating the information available in an attempt to avoid possible errors in diagnosis by house staff and internists. There are two mechanisms that might mediate ECG changes in patients with SAH, i.e. autonomic neural stimulation from the hypothalamus or elevated levels of circulating catecholamine. Hypothalamic stimulation may cause ECG changes without associated myocardial damage whereas elevated catecholamine levels have been correlated with QT-interval prolongation and myocardial damage.