A cross-sectional study of 140 healthy, non-obese women and growing girls aged 8-27 y was undertaken to examine changes in total-body and regional fat and fat-free lean tissue mass by Tanner stage of pubertal development with dual-energy X-ray absorptiometry. Absolute fat mass and absolute fat-free lean tissue mass were higher at successive Tanner stages (1 through 5) but the proportional increase was greater for fat: total fat mass (kg) was about threefold higher in Tanner stage 5 than in stage 1 (P < 0.001), whereas lean tissue mass (kg) in Tanner stage 5 was about double that in stage 1 (P < 0.001). Furthermore, although the regional distribution of lean tissue mass in the trunk and legs remained fairly constant at different pubertal stages, the regional distribution of fat was altered significantly, becoming more central and less peripheral. Trunk fat (as a percentage of total body fat) was significantly higher at stage 5 than at stage 1 (P < 0.001). In the whole population, body mass index was positively correlated with trunk fat (r = 0.662, P < 0.0001) and negatively with leg fat (r = -0.457, P < 0.0001). We conclude that girls accumulate a higher proportion of their total adult fat mass than of their total adult lean tissue mass during puberty, and that regional fat patterns become more android and less gynoid with maturity.