The association of sarcoidosis and chylothorax is rare. A patient aged 64 presented with mediastinal sarcoidosis. Two years after the diagnosis he developed a right chylothorax. The computed tomographic examination showed a retraction of the right hemithorax associated with large mediastinal nodes, without signs of interstitial lung disease. Pulmonary function tests revealed a restrictive ventilatory defect with a Forced Vital Capacity (FVC) of 53% and a Forced Expired Volume in one second (FEV1) of 54% from the predicted values; the FEV1/FVC ratio was 78%. Steroid therapy was started at 1 mg per kilogram per day for three months then progressively decreased to 15 mg per day. Inspite of the steroid therapy there was as well biological evidence of continued disease activity (bronchoalveolar lavage lymphocytosis and increased serum angiotensin converting enzyme), as persistence of pleural effusion and mediastinal adenopathy; the contraction of the right hemithorax increased. Restrictive ventilatory defect worsened with a FVC of 44% and an FEV1 of 47% of the predicted values. The presence of a significant contraction of the hemithorax and of a severe restrictive ventilatory defect suggested the existence both of pleural fibrosis and of a compression of the main lymphatic pathways responsible for the chylothorax.