Acute symptomatic tachyarrhythmias are commonly seen by emergency unit personnel. Electrical cardioversion is often used at Groote Schuur Hospital to treat such patients because of concerns about the safety and efficacy of intravenous anti-arrhythmic agents. All patients presenting with acute symptomatic tachyarrhythmias who were managed only by the staff of the Emergency Unit were entered into the study to assess the efficacy and safety of direct current (DC) cardioversion. Those with sinus tachycardia or atrial fibrillation of more than 24 hours' duration were excluded. Staff, on joining the unit, were instructed in the use and technique of DC cardioversion, and given simple guidelines for the management of acute tachyarrhythmias. Fifty-three patient events were seen over a period of 16 months: 7 patients had ventricular tachycardia, 21 had atrial flutter, 20 had paroxysmal junctional re-entry tachycardia, 4 had atrial fibrillation and 1 had multifocal atrial tachycardia. Fifty-two were successfully converted to sinus rhythm. One patient with atrial flutter and 9 with paroxysmal junctional re-entry tachycardia reverted after undergoing vagal manoeuvres or receiving intravenous verapamil. Of the remaining 43 patients, 42 (98%) were cardioverted with synchronised DC shock under midazolam sedation (7/7 ventricular tachycardia, 20/20 atrial flutter, 11/11 paroxysmal junctional re-entry tachycardia, 4/4 atrial fibrillation, 0/1 multifocal atrial tachycardia). Four patients had their sedation electively reversed with flumazenil. No complications occurred. DC cardioversion was only considered inappropriate in the 1 patient with multifocal atrial tachycardia. This study shows that if simple guidelines are followed, non-cardiologist junior medical personnel can safely and effectively manage sustained, acute, symptomatic tachyarrhythmias by employing DC cardioversion as and when appropriate.