We determined the applicability of deriving the stature from knee height in an older Italian population, and, in the same population, we assessed longitudinally the change in stature over a 6-year interval. The standing stature and knee height in a supine position were measured in the entire home-dwelling older (65 + years) population of a small Italian town (N = 606). Stature measured in 1989 and in 1995 was used to assess longitudinal changes in 258 subjects of the same population. Stature derived from knee height was greater than measured stature in this population and in the two sexes. This difference disappeared when subjects with evident kyphosis were excluded. From 1989 to 1995, stature decreased by 1.7+/-3.0 cm, with women showing a larger decrement than men. Stature estimated from knee height is more accurate than measured stature in subjects with kyphosis. In accordance with previous studies, stature decreases with aging, and such height loss is greater in women than in men.