We examined age-related changes of the entire skeleton and its major anatomical areas (spine, trunk, pelvis, arms, legs) in 139 healthy males (19-99 years of age) and evaluated the influence of lean mass and fat mass on these changes. The population studied was stratified according to their ages referred in decades. Bone mineral density (BMD) and body composition (fat mass, lean mass) were measured by Lunar DPX. A negative linear correlation between BMD values and age was observed. The overall bone loss from the young to the aged was statistically significant for all skeletal sites, with a lower level of significance for the spinal area: BMD percentage decrease ranged from 19.4% for the pelvis to 9% for the spine. Peak bone mass was observed in the first decade (19-29 years of age). Soft tissue increased until the fifth and sixth decades, followed by a gradual decrease. Lean mass declined in a uniform way from the first to the last decades. BMD values were significantly related to lean mass, but there were no correlations with the fat mass. Lean body mass was significantly related to BMD/height, index of "true" volumetric density. Multiple regression analysis confirmed that in males the principal determinant of total body bone density is fat-free mass.