We reviewed the radiologic, physiologic, and pathologic features of biopsy-proved pulmonary 1ymphangioeiomyomatosis(LAM) in 2 patients. Chest radiogra;hs showed diffuse increased interstitial lung markings with normal or slightly increased lung volume. The prominent computed tomographic(CT) feature was thin walled cysts throughout the lungs. Pulmonary function test showed a mixed obstructive and restrictive pattern in one and a mainly restrictive pattern in another, which was somewhat different from that of the reported cases. Proliferation of smooth muscle cells in the 1ymphatics, alveolar septae, vessels, and bronchioles wasthe pathologic finding.