The Drinkwater-Ross anthropometric fractionation of body mass (mass = sigma skeletal, residual, fat and muscle masses), lean body mass (LBM = sigma skeletal, residual and muscle masses) and fat mass (FM) were compared with the measured body mass, together with the densitometrically estimated fat-free mass (FFM) and fat mass (FM), of 205 male (mean +/- S.D.: 74.66 +/- 10.55 kg; 10.1 +/- 3.7% BF by densitometry) and 177 female (mean +/- S.D.: 59.14 +/- 8.85 kg; 18.5 +/- 5.1% BF by densitometry) South Australian State representatives in a variety of sports. Most absolute differences (d) between the measured body masses and those resultant from the sum of the four fractionated masses (male: d = 2.15 kg or 2.9%; female: d = 1.27 kg or 2.2%) were within what one would expect from random day-to-day variation. However, this was not so for the comparisons between the fractionated LBM (male: d = 2.54 kg or 3.8%; female: d = 2.45 kg or 5.2%) and FM scores (male: d = 1.67 kg or 30.0%; female: d = 2.40 kg or 20.0%) and their densitometric counterparts. These differences are probably related to a combination of the densitometric and fractionation assumptions.