Estrogen and progesterone receptors were demonstrated immunocytochemically in the lung tissue of two cases of pulmonary lymphangioleiomyomatosis. In one case both receptors were localized in the proliferative smooth muscle nodules and diffusely in the interstitial tissue in close proximity to the muscle. The pulmonary tissue in the other case contained the estrogen receptor only. The authors conclude that the response to hormonal treatment seen in this disease might be optimized in the future by monitoring for the presence of steroid hormone receptors.