INTRODUCTION:Normal values of the 6-min walk distance (6MWD) for children have not been well demonstrated. This limits the interpretation of the 6MWD in children. METHODS: A crosssectional prospective study was designed. A total of 949 (467 males, 482 females) healthy children were recruited randomly from 7 Turkish secondary schools in Ankara. The 6-min walk tests were conducted according to the American Thoracic Society guidelines. RESULTS: The mean 6MWD decreased between the ages of 12 and 14 y for both boys and girls, and then gradually increased until 17 y of age. In the best fitting and most efficient linear, quadratic, and categorical regression models, the age of the subjects, heart rate after the test, and physical activity level of the subjects were significantly related to the 6MWD. Nevertheless, these variables explained < 20% of the variance in the 6MWD. CONCLUSIONS: The 6MWD does not increase in a straight linear fashion from the age of 12 until adulthood. Correlation of the 6MWD with anthropometric features is very weak, so in evaluating the 6MWD, the standard curves should be used.