Direct current cardioversion is a common management option for termination of tachydysrhythmias, including atrial fibrillation and atrial flutter. It is generally safe and effective with infrequent reporting of side effects. Pulmonary edema is a rare complication with reported incidence of 1-3% and mortality of 18%. Our literature search did not reveal any reported cases of postcardioversion pulmonary edema in the emergency medicine literature.We report a case of an 80-year-old woman with a history of atypical atrial flutter on warfarin, paroxysmal atrial fibrillation, and rheumatic mitral valve disease who presented with shortness of breath 12 h after transesophageal echocardiography and subsequent direct current cardioversion with reversion to sinus rhythm. She was found to be in acute pulmonary edema. She was placed on noninvasive ventilation and diuresis with eventual symptom resolution. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Postcardioversion pulmonary edema is a rare complication that may occur after reversion to sinus rhythm. Emergency physicians should be cognizant of patients, especially those with underlying structural heart disease, who present with dyspnea after a recent cardioversion procedure or after cardioversion in the emergency department. Patients cardioverted in the emergency department may be observed for around 3 h and counseled on the development of respiratory symptoms.