This longitudinal study was undertaken to ascertain the rate of bone loss and to identify aging, cohort and/or time effects on bone loss in male participants of the Baltimore Longitudinal Study of Aging. Hand-wrist radiographs were obtained from 1958-1981 and were evaluated for total width, medullary width, and length of the second metacarpal. Data were analyzed using an age-time matrix with 8-year intervals for three epochs and nine age groups. The bone measurements were analyzed in three perspectives (cross-sectional, longitudinal and time-series). The results demonstrate that there is both a cross-sectional and longitudinal loss of cortical bone with age in the second metacarpal. Furthermore, the results show that males lose approximately 14% of their cortical bone, at a rate of about 2% per decade, over the adult lifespan. The majority of this loss occurs between the ages of 45 and 69 and is due primarily to aging and is not an artifact of cohort differences or secular change.