Androgen deprivation therapy is the mainstay of treatment for advanced prostate cancer. There is an increasing tendency towards earlier treatment with hormone manipulation. However, luteinizing hormone-releasing agonists decrease serum testosterone to castrate levels within two weeks of commencement.They are associated with loss of libido, loss of muscle bulk and accelerated bone loss. Osteoporotic patients are at high risk of fragility fractures. An alternative is the nonsteroidal antiandrogen bicalutamide which blocks testosterone at the receptor level, allowing androgen deprivation in the prostate without reducing circulating levels of testosterone. This should preserve the desired effects on other androgen-sensitive tissue, resulting in an advantageous side effect profile. The aim of our study is to closely monitor osteoporotic patients commencing bicalutamide for a period of 12 months. Patients will be reviewed in a dedicated prostate cancer clinic every 3 months. Patients will be questioned regarding adverse events. Renal and liver function tests, prostate specific antigen, testosterone, estradiol and bone turnover markers will be measured 3 monthly. Measurement of height , weight, body mass index, quadriceps strength using dynamometry, and skeletal mass using arm anthropometry (mid-arm circumference and triceps skinfold thickness), will be carried out 3 monthly. Quality of life issues will be assessed 3 monthly using the Rand 36-Item Health Survey (SF36) and University of California-Los Angeles Prostate Cancer Index (UCLAPCI). Patients will undergo bone densitometry of the forearm at baseline and 12 months.