['Current androgen deprivation therapies for men with prostate cancer cause accelerated osteoporosis and a significant risk of osteoporotic fracture. We have recently shown that transdermal estradiol is an effective alternative for such patients. Here we report the impact of transdermal estradiol therapy on the bone mineral density of men with prostate cancer.', 'A total of 20 patients with newly diagnosed locally advanced or metastatic prostate cancer were treated with transdermal estradiol patches. Bone mineral density of the lumbar spine and the proximal femur was measured with dual-energy x-ray absorptiometry, and correlated with computerized tomography and isotope bone scan findings at 6-month intervals.', "In all measured regions bone mineral density increased with time. By 1 year mean bone mineral density +/- SEM had increased by 3.60% +/- 1.6% in the lumbar spine (p = 0.055), 2.19% +/- 1.03% in the femoral neck (p = 0.055), 3.76% +/- 1.35% in the Ward's region (p = 0.008) and 1.90% +/- 0.85% in the total hip (p = 0.031), respectively. Of 12 osteoporotic sites 4 had improvement based on World Health Organization grading. All other sites improved toward a better classification."] Does transdermal estradiol improve bone density when used as single agent therapy for prostate cancer?