During open mitral commissurotomy in a patient with mitral stenosis, a vent catheter retention ring was accidentally slipped off into the left atrium and lodged near the orifice of the right renal artery. Nonsurgical retrieval of this intraarterial foreign body was performed successfully under fluoroscopic guidance in the operating room using a combined approach of angiographic catheters and guidewire, these being inserted via the arteriotomy site of the right femoral artery created for cardiopulmonary bypass.