We assessed the criterion-related validity of Cureton’s equation for estimating peak oxygen consumption (VO2peak) from the one-mile run/walk test in endurance-trained children aged 8-17 years. Altogether, 66 physically active white children and adolescents (32 girls, 34 boys) completed a graded exercise test to volitional exhaustion and the one-mile run/walk test. Cureton’s equation was used to estimate VO2peak, and was assessed using several error measures. Agreement between measured VO2peak and estimated VO2peak was analysed by the Bland and Altman method. The correlation coefficient between measured VO2peak and one-mile run/walk time was -0.59 (P0.001) and that between measured and estimated VO2peak was 0.70 (P0.001). The mean difference between measured and estimated VO2peak was 10mlkg-1min-1 (95% CI=9.2-11.8; P0.001). The standard error of the estimate was 3mlkg-1min-1, and the percentage error was 32%. There was a positive association between the measured and estimated VO2peak difference and the measured and estimated VO2peak mean, which indicates that the higher the VO2peak the higher the error of the estimate. These findings did not change markedly when the analyses were performed by sex, age group or body mass status. These results suggest that Cureton’s equation systematically underestimates VO2peak in endurance-trained children with high VO2peak.