Bronchogenic cysts are developmental foregut anomalies usually located within the mediastinum or lung parenchyma. An isolated bronchogenic cyst of the diaphragm is very rare. Our case was a 56-year-old female patient who presented with pleuritic chest pain in her right chest. Chest and abdominal computed tomography revealed a large lobulated cystic mass that was accompanied with pleural effusion in the right lower hemithorax. The tumor showed focally calcified areas in the wall and abutted against the diaphragm. We performed complete excision of the cyst including a portion of the diaphragm attached to it. The pathological diagnosis was established as the bronchogenic cyst originating from the diaphragm. We report this case with a review of the literature.