Involutional osteopenia is the most common metabolic bone disorder affecting the elderly population. Improved diagnostic techniques now allow for earlier detection of a decrease in bone mass than is possible with routine skeletal roentgenograms. Methods developed for quantitating bone remodeling have given new insight to the mechanisms involved in age-related skeletal loss. Theories of pathogenesis include  inadequate skeletal acquisition during youth,  dietary deficiencies of calcium and vitamin D,  hormonal imbalance, and  local factors influencing skeletal remodeling, particularly at the endosteal envelope. Numerous agents affecting bone remodeling have been used to treat involutional osteopenia, but none has been proved to restore bone mass. New programs involving combinations of agents give promise for increasing bone mineral content and, it is hoped, reducing fracture rate.