In men, osteoporosis is a prevalent problem that is under-recognized and undertreated. Men 50 years and older have a 13% lifetime risk for fracture. Hip and vertebral fractures are associated with significant functional impairment and increased mortality in men. The morbidity and mortality following a fracture is also greater in men than it is in women. By improving our knowledge on the pathophysiology of osteoporosis in men, better management strategies for this condition may be developed. In recent years, there has been greater awareness of the biomechanic factors that contribute to bone strength, which may explain some of the differences in fracture incidence between men and women. There is also growing evidence to support the key role of estrogens in maintaining bone health in older men, similar to women. This review highlights our current understandings on the epidemiology and pathophysiology of male osteoporosis and its related fractures, with particular focus on the determinants of bone strength and the role of sex hormones on bone metabolism in men.