Pulmonary lymphangiomyomatosis (LAM) is a rare and serious disease in women of reproductive age, in which hamartomatous smooth muscle proliferation occurs in lymphatics. The most frequent presenting symptoms or complications are dyspnea, chylothorax and pneumothorax. Chest X-ray reveals a diffuse interstitial infiltrate associated, curiously, with airflow obstruction, air trapping and even hyperinflation. In more than a third of cases, pulmonary LAM coexists with a rare renal tumor, angiomyolipoma. Two new cases additional to the hundred published are reported. The first patient died undiagnosed after a typical seven years' evolution including removal of a renal angiomyolipoma late in the disease. In the second case a renal angiomyolipoma was excised several years before the first respiratory symptoms; at the time of diagnosis there was already severe airflow obstruction now stable under treatment with progesterone. Early hormonal therapy with medroxyprogesterone seems to be the only treatment likely to improve this disease, whose prognosis is usually fatal. Previous attempts to treat LAM are also discussed.