Objective. The aim of this study was to analyse the prevalence of osteoporosis and risk factors of osteoporotic fractures before androgen deprivation in Danish men. Treatment and prognosis of prostate cancer necessitate management of long-term consequences of androgen deprivation therapy (ADT), including accelerated bone loss resulting in osteoporosis. Osteoporotic fractures are associated with excess morbidity and mortality. Material and methods. Patients with prostate cancer awaiting initiation of ADT were consecutively included. Half of the patients had localized disease and were referred for curative intended radiation, and the remaining patients had disseminated disease. Blood samples were collected, a questionnaire was administered and a dual-energy X-ray absorptiometry (DXA) scan was performed before initiating ADT. The patients were included between January 2010 and March 2012. The study was approved by the local ethics committee. None of the patients had received prior androgen deprivation or osteoporosis treatment. Results. In total, 105 individuals were included. The mean age of the participants was 70 years (range 53-91 years, SD 6.3). The median prostate-specific antigen level was 30.5 g/l (1-5714 g/l). The average Gleason score was 7.8 (range 5-10, SD 1.1). Fifty patients had localized prostate cancer and the other 55 patients had disseminated disease. The prevalence of osteoporosis was 10% and the prevalence of osteopenia was 58% before ADT. There was no significant difference between the two subgroups concerning osteoporosis. Smoking use was the only factor that was significantly associated with an increased prevalence of osteoporosis in the study population. Conclusion. Two-thirds of patients with prostate cancer awaiting ADT had osteoporosis or reduced bone mass. Further awareness regarding osteoporosis and bone health in prostate cancer is needed. It is suggested that patients with prostate cancer undergo a DXA scan before starting ADT.