A 54-year-old man presented with sudden and severe abdominal pain, and vomiting. He had underwent a right pneumonectomy with bronchial stump reinforcement using diaphragmatic muscle flap 9 years ago, due to non-small cell lung cancer after neoadjuvant chemotherapy. A right partial visceral herniation had been detected 5 years ago during the follow-up which was not present at previous visits. He had refused any surgical intervention since he had been asymptomatic. The chest computed tomography demonstrated visceral herniation. The patient underwent an urgent operation via thoracoabdominal incision to repair the herniation. This type of late catastrophic complication of diaphragmatic muscle flap reinforcement is extremely rare.