Previous research in this laboratory, using relatively lean males, indicated that the skinfold caliper and ultrasound techniques gave similar predictions of body density. The present study compared caliper with ultrasound measurements in predicting body density of 44 white, obese, free-living adult volunteers of both sexes. Subcutaneous-fat thickness was measured at six body sites with a Lange caliper and an ADR 2130 ultrasound scanner. By hydrostatic weighing, mean (+/- SD) body density was 1.01 g/mL (+/- 0.02) and percentage body fat, 41.7% (+/- 7.8). The best predictors of body density were the thigh and biceps sites with ultrasound (r = 0.820) and the triceps site with the calipers (r = 0.633). Further, ultrasound proved to be superior to the caliper technique in measuring subcutaneous fat of obese persons.