Estrogen deficiency and pulmonary diseases are associated with bone mineral density (BMD) loss. Lymphangioleiomyomatosis (LAM), a disorder affecting women that is characterized by cystic lung lesions, is frequently treated with antiestrogen therapy, i.e., progesterone and/or oophorectomy. Therefore, we evaluated BMD yearly in 211 LAM patients to determine the prevalence of BMD abnormalities, whether antiestrogen therapy decreased BMD, and if treatment with bisphosphonates prevented bone loss. Abnormal BMD was found in 70% of the patients and correlated with severity of lung disease and age. Greater severity of lung disease, menopause, and oophorectomy were associated with greater decline in BMD. After adjusting for differences in initial lung function and BMD, we found similar rates of BMD decline in progesterone-treated (n = 122) and untreated patients (n = 89). After similar adjustments, we found that bisphosphonate-treated patients (n = 98) had lower rates of decline in lumbar spine BMD (-0.004 +/- 0.003 vs. -0.015 +/- 0.003 gm/cm(2), p = 0.036) and T-scores (-0.050 +/- 0.041 vs. -0.191 +/- 0.041, p < 0.001) than untreated patients (n = 113). We conclude that abnormal BMD was frequent in LAM. Progesterone therapy was not associated with changes in BMD; bisphosphonate therapy was associated with lower rates of bone loss. We recommend systematic evaluation of BMD and early treatment with bisphosphonates for patients with LAM.