This report describes a case of defecation syncope secondary to functional inferior vena cava (IVC) obstruction. Preoperative hemodynamic assessment revealed a marked decrease in blood pressure and IVC obstruction when the patient performed a Valsalva maneuver. The intraoperative approach included continuous hemodynamic monitoring as well as transesophageal ultrasonography to assess IVC patency during surgical mobilization of the IVC. Functional obstruction of the IVC at the diaphragmatic hiatus was identified, and this obstruction was relieved with extensive mobilization of the IVC and right crural myotomy. This report describes an effective surgical approach to a rare functional disorder involving the IVC.