Male osteoporosis is challenging to diagnose and to treat. Underestimation of the risk of male osteoporosis, the combined presence of several interwoven causative factors in many patients, and uncertainty regarding the absorptiometry cutoffs associated with fractures are major obstacles to the diagnosis of male osteoporosis and to the identification of men at risk for fractures. The lifetime risk of osteoporotic fracture is estimated at 15% among men older than 50 years. One-third of proximal femoral fractures occur in men, and the associated mortality rate is 2- to 3-fold that in women. In men, nearly half the cases of osteoporosis are related to disease, medications, or risk factors. Although the criteria for diagnosing male osteoporosis are not agreed on, the definitions developed by the World Health Organization can be used provided the reference population is composed of young males. An absorptiometry T-score < or = -2.5 is useful for diagnosing osteoporosis but fails to adequately predict the fracture risk. The identification of men at high risk for fractures requires a combined evaluation of bone mineral density data, clinical risk factors, and risk factors for falls.