The effect of androgen on bone metabolism still remains unknown. However the efficacy of androgen replacement therapy for bone health in patient with late-onset hypogonadism (andropause) has been elucidated to date. Gain in lumber bone mineral density by androgen replacement therapy has been presented but not in femoral neck bone mineral density. No trial measured or reported the effect of androgen on fractures. Progression of osteoporosis and bone fracture in aging male populations is a serious concern not only as medical aspect but also as administrative issue in the developed nations where aging peoples has been increasing. A well-controlled larger clinical study to test androgen replacement therapy for aging male is expected also in Japan.