BACKGROUND: Post myocardial infarction arrhythmias can very commonly lead to death. Hence we studied the various arrhythmias arisingwithintherst24hours ofmyocardialinfarction. METHODS: Myocardial infarction was conrmed with detailed history, clinical examination, laboratory investigations, and 12 lead electrocardiogram. 50 patients who presented within 1 hour of onset ofsymptoms were included in study. Patients' cardiac rhythm was monitored for at least 72 hours in intensive coronary care unit. RESULTS:IncidenceofvariousTachyarrhythmiaswere: 1. Ventriculartachycardia (8%), 2. AtrialFibrillation(4%), 3. Supraventriculartachycardia (2%). 4. Ventricularbrillationwas notobserved. CONCLUSION:Arrhythmias carrying very high mortality were complete heart block, bilateral bundle branch block and right bundle branch block. Arrhythmiaswithanteriorwallinfarctioncarriedbadprognosiswhile arrhythmiaswithinferiorwallinfarctionhadgoodprognosis.