We report a retrospective analysis of 5 years of adenosine use in our emergency department (2002-2006). We treated 454 patients with an intravenous bolus of adenosine. The cohort was made up of 40.7% men and 59.3% women, with mean age of 47.32 years, mean heart rate of 162.48 beats per minute. Among them, 73% responded immediately to the 6-mg dose, 15% responded after the second 12-mg dose, and 11% responded to a further 12-mg dose, whereas 11% were unresponsive. We observed minor side effects in a high percentage of patients (ie, chest tightness 83%, flushing 39.4%, sense of impending death 7%). Only 1 major adverse effect was recorded, that is, administering 12 mg of adenosine induced a marked acceleration in the ventricular rate of a patient with an undiagnosed atrial flutter, caused by induction of atrioventricular conduction (1:1). Our results confirm that when patients are appropriately selected, adenosine is probably the best available drug to treat paroxysmal supraventricular tachycardias, especially in emergency situations.