Pulmonary lymphangiomyomatosis is a rare but distinct clinical and pathological entity. It is characterized by hamartomatous proliferation of smooth muscle around the lymphatic vessels of the lung, mediastinum, and retroperitoneum. It occurs only in menstruating women and girls and is manifested by spontaneous pneumothorax and chylous pleural or abdominal effusion. As it progresses, the lungs become increasingly involved with subsequent pulmonary insufficiency and recurrent infection. Eventually death results. This entity has not been reported previously in the surgical literature even though the thoracic surgeon is called on to both establish the diagnosis and aid in palliation. The hypothesis that the disease is estrogen dependent is reviewed and the desirability of estrogen ablation in patients with positive estrogen receptors is suggested.