A 41-year-old female patient presenting with chylothorax was found to have pulmonary lymphangiomyomatosis. Recurrence led to parietal pleurectomy. Lung biopsy performed at surgery confirmed the histology diagnosis. Hormone treatment with medroxyprogesterone acetate was initiated immediately and administered via intramuscular injections each month. The treatment was continued for three years and regular clinical, functional and radiologic follow-up provided evidence of response: radiologic and functional stability were achieved at the cost of major secondary effects of hormone therapy. This rare, apparently hormone-dependent, disease raises the problem of the long-term benefit of treatment.