Congenital chylothorax in a male infant persisted for 10 weeks despite repeated thoracocenteses and dietary regimens which included total parenteral nutrition for 37 days and a peroral semielementary diet with medium-chain triglyceride content for 19 days. Thoracotomy disclosed a small leak in the thoracic duct. The duct was ligated above and below the leak, as attempted repair was unsuccessful. There was no recurrence of pleural effusion after the operation and no distal lymphoedema was observed.