A 64-year-old man presented with a massive right-sided hydrothorax associated with cirrhosis of the liver. There was no clinical evidence of ascites nor other underlying disease. The usual complementary tests failed to demonstrate any causative abnormality. Chest and abdominal scintigraphy after intraperitoneal injection of 99mTc-human serum albumin disclosed early filling of the pleural space by the radiopharmaceutical and suggested a diaphragmatic defect as the cause for this rare association.