This study was designed to compare air displacement plethysmography with dual-energy X-ray absorptiometry (DXA) and 3 other field methods for estimation of body composition. Subjects were 62 healthy, white men aged 37.6+/-2.9 y (weight: 81.8+/-11.3 kg; height: 171.5+/-4.9 cm). Body composition was also assessed by using body mass index, single-frequency bioelectrical impedance analysis, multi-frequency bioelectrical impedance spectroscopy, and the skinfold-thickness equations of Jackson and Pollock and Durnin and Womersley. Percentage body fat (%BF) with the plethysmograph was 23.4+/-7.0 and with DXA was 26.0+/-7.4. The 2.6% mean difference was significant (P< 0.05). Total error was 3.7%BF. As assessed by multiple regression analysis, %BF with the plethysmograph, age, weight, and height yielded a DXA-adjusted R2 value of 89.5% fat and an SEE of 2.4% fat. All other models had higher SEEs and lower adjusted R2 values: 4.3% and 66.5% for body mass index, 3.3% and 79.8% for bioelectrical impedance analysis, 3.6% and 76.2% for bioelectrical impedance spectroscopy, 3.7% and 74.55% for the equations of Jackson and Pollock, and 3.9% and 71.6% for the equations of Durnin and Womersley, respectively. The plethysmograph also predicted fat mass and fat-free mass more accurately than all other models, with a lower SEE and higher adjusted R2 value. In conclusion, although %BF was systematically underestimated, body composition was closely estimated with air displacement plethysmography in middle-aged men.