Patients with extensive peritoneal spread from advanced ovarian cancer often undergo several upper abdominal surgical procedures including subphrenic peritonectomy to obtain optimal cytoreduction. The most common complications are pleural effusions, pancreatic leakage and endoabdominal collections. This case report describes an unusual complication, a diaphragmatic hernia with an intrathoracic gastric volvulus developing four months after the patient underwent left subphrenic peritonectomy during interval debulking surgery and hyperthermic intraperitoneal chemotherapy for advanced ovarian cancer.