Osteoporosis is often considered a disease of women. However, the lifetime risk of osteoporotic fracture in men is as high as 1 in 4. Furthermore, approximately 30% of hip fractures occur in males. Additionally, morbidity and mortality following osteoporotic fractures appears to be greater in men than women. Thus, it is appropriate that increased attention be paid to this problem in men. Recently, indications for bone mass measurement in men have been published. They include prior low trauma fracture, hypogonadism, and corticosteroid treatment, among others. Additionally, a consensus recommendation that osteoporosis be diagnosed at a T-score of -2.5 or below will soon be published. In men presenting with low bone mass or osteoporotic fractures, secondary causes of bone loss will be found in up to two thirds. The most common secondary causes are corticosteroid use, alcohol abuse, hypogonadism, and idiopathic hypercalciuria. Thus, laboratory evaluation is indicated in osteoporotic men. Finally pharmacologic agents to treat osteoporosis have recently been approved in men. This review highlights current understanding of epidemiology, pathophysiology, diagnosis, and treatment of osteoporosis in men.