External direct current (DC) cardioversion is a commonly used method of terminating atrial arrhythmias. The chance of procedural success is inversely related to the duration of the arrhythmia. In many hospitals, the procedure is carried out under general anaesthesia, necessitating the presence of anaesthetic as well as medical staff. Frequently, it may be difficult to coordinate the availability of the two teams, causing delays to each patient, waste of staff time, an inefficient service and increased costs. The primary aim of the study was to determine the safety and tolerability of conscious sedation using intravenous midazolam in elective external DC cardioversion of patients with atrial flutter or atrial fibrillation attending University Hospital Limerick, Ireland. Patients who were electively admitted for DC cardioversion for atrial fibrillation or atrial flutter were recruited. A pre-defined sedation protocol using intravenous midazolam was used. The midazolam was given by the cardiology registrar without the presence of an anaesthetist. DC cardioversion was then performed according to the hospital protocol. Any complications arising during the procedure were noted. Prior to discharge, patients were given a questionnaire to determine their awareness of the procedure and if they would have the procedure done again in the future if needed. A total of 100 patients were recruited. The median number of shocks was one (highest number of shocks being four). The median dose of midazolam was 7.5 mg, with the highest dose being 20 mg. All of patients surveyed were not aware of the shock that was administered to them. All of the patients surveyed were happy with the service and would be happy to return for a repeat cardioversion in the future if required. The use of conscious sedation for DC cardioversion of patients with atrial fibrillation / atrial flutter was found to be safe and tolerable.