Atrial septal defects are among the most common congenital heart defects seen in the adult population. The diagnosis is usually made in children and closure is attempted before they are school age. In other cases, where the diagnosis is missed until adulthood, atrial arrhythmias and congestive heart failure are commonly seen. We report the case of an atrial septal defect (secundum type), which was diagnosed in a 72-year-old woman with paroxysmal atrial fibrillation. She also had a history of hypertension and hyperlipidemia. Transthoracic and transesophageal findings were consistent with right-sided volume overload and an atrial septal defect of approximately 1 cm in size. This was corroborated by the findings on cardiac catheterization with a shunt ratio of 1.8. The pulmonary artery pressures were within normal limits. The patient was referred for closure of the atrial septal defect. Presently, the options for septal defect closure are direct suture repair, Dacron patch repair depending on the size of the defect, and percutaneous transcatheter closure. Transcatheter closure is also available in treating selected patients with patent foramen ovale.