The aim of this study was to investigate the relationships between adiposity and skeletal maturity, relative skeletal maturity and percentage of predicted adult stature. A representative sample of 6,029 Flemish girls aged 6-16 years of age was investigated. Age specific correlations between adiposity and biological maturity indicators were calculated and in each age group the fattest 5% were compared with the leanest 5%. Adiposity was estimated from the sum of five skinfolds (biceps, triceps, subscapular, suprailiac and medial calf). Skeletal age was assessed according to the Tanner-Whitehouse technique. Relative skeletal age was calculated as the difference between skeletal age and chronological age and percentage of predicted adult stature was calculated according to the Tanner-Whitehouse Mark II regression technique. Correlations between adiposity and maturity indicators are positive, but vary between r = 0.00 and r = 0.39. When stature is statistically controlled, correlations are reduced slightly. The 5% fattest girls are equally advanced (0.2 to 1.2 years) as the 5% leanest girls are delayed (0.0 to 0.9 years) in skeletal maturation. Attained statures are consistent with the maturity data and indicate that size differences between fat and lean girls are primarily due to maturity differences. It was concluded that during childhood and adolescence, fatness is associated with advanced and leanness with delayed biological maturity status. This association seems to have long term effects that merit further study.