This study compared the validity of reported equations as predictors of peak VO(2) in 8-10-year-old children. Participants (90 boys and girls aged 8-10 years) performed the multistage-shuttle-run-test (MSRT) and peak VO(2) was measured in field using a portable gas analyser. The equations that estimated peak VO(2) from the MSRT performance were chosen according to the age range of this study. As follows, the FITNESSGRAM reports and the equations of Leger et al. (Can J Appl Sport Sci 5: 77-84, 1988), Barnett et al. (Pediatr Exerc Sci 5:42-50, 1993), Matsuzaka et al. (Pediatr Exerc Sci 16:113-125, 2004) and Fernhall et al. (Am J Ment Retard 102:602-612, 1998) were used to estimate the peak VO(2) and compared with the directly measured value. The equation of Leger et al. (Can J Appl Sport Sci 5: 77-84, 1988) provided a mean difference (d) of 4.7 ml kg(-1) min(-1) and a 1.0 slope. The equation of Matsuzaka et al. (Pediatr Exerc Sci 16:113-125, 2004)(a) using maximal speed (MS) showed a higher d (5.4) than the remaining using total laps d (4.2). The equation of Barnett et al. (Pediatr Exerc Sci 5:42-50, 1993)(a) that includes triceps skinfold and MS showed the highest d (6.1) but the smallest range (24.1) and slope (0.6). Data from the FITNESSGRAM had the smallest d (1.8 ml kg(-1) min(-1)), but also had the highest range between limits of agreement (28.6 ml kg(-1) min(-1)) and a 1.2 slope. The lowest slope (0.4) and range (22.2 ml kg(-1) min(-1)) were observed using the equation of Fernhall et al. (Am J Ment Retard 102:602-612, 1998). Log transformation of the data revealed that the equations of Matsuzaka et al. (Pediatr Exerc Sci 16:113-125, 2004)(a) (1.1*/÷1.25) and Fernhall et al. (Am J Ment Retard 102:602-612, 1998) (1.17*/÷1.25) showed the closest agreement among all, but they still yield unsatisfactory accuracy.