Osteoporosis has long been considered to be a disease of the aging female skeleton. As awareness of the pervasiveness of this disorder heightens, men are also being shown to be at risk for osteoporosis. The purpose of this article is to review what is known about the factors in the male that lead to acquisition, maintenance and loss of bone, as well as new insights into a group of men whose osteoporosis, although severe, remains to be explained.