Aim <p>To test whether the 3-min Walk Test is a valid alternative to the 6-min Walk Test in typically developing children.</p> Method <p>Prospective study involving typically developing children at primary school was undertaken. The distance (m) covered during long-distance walking was measured using the 6-min Walk Test and recorded at 3 and 6&#xa0;minutes.</p> Results <p>1512 typically developing children from 12 schools were measured. The children’s ages ranged from 6 to 12 years old, with a mean age of 9.4 years (SD 1.8), and 761 (50%) were male. The mean distance covered during the 6-min Walk Test was 628&#xa0;m (SD 77) and 325&#xa0;m (SD 41) during the 3-min Walk Test. Mean distance covered during the 6-min Walk Test was 1.9 times the distance covered during 3-min Walk Test and this relationship held true for both sexes until age 12 years old where it increased to 2.0 times. Correlation between the distance covered in the 6-min Walk Test and the 3-min Walk Test was very strong, at <i>r</i> = 0.91 (95% CI 0.90 to 0.92). Hold out validation showed that the model was not overfitting, and prediction accuracy was supported by a small standard error of estimate, suggesting that the results are generalizable.</p> Discussions/ conclusions <p>The 3-min Walk Test is a valid alternative to the 6-min Walk Test in typically developing children and it can be used to predict the 6-min Walk Test.</p>