Value of a clinical test for assessing physical activity in children Background: An appropriate measurement of physical activity (PA) in children is useful, since inactivity is associated to obesity, cardiovascular and metabolic risk. Aim: To assess the reliability of the INTA questionnaire of PA, to compare the derived PA score with accelerometry and to assess its ability to identify excessively inactive children. Material and methods: One hundred eighty children aged 8 to 13 years answered an interviewer-administered questionnaire about their usual PA, consisting in 5 items (recumbent, seated, walking, playing outdoor, sports). The answers were converted to a PA score with a 0-10 points scale. Reliability was tested in 87 children by test/retest conducted 3-5 days apart. The PA score was compared with 3-day accelerometry in 77 of 93 children (35 obese and 42 non obese). Receiver operating characteristic (ROC) curves were used to determine the optimal cutpoint for identify an excessively sedentary child. Results: The test/retest reliability of the questionnaire was 0.69 to 0.93 (Lin coefficient). Accelerometry was significantly associated with PA score (RHO: 0.60, p =0.008), outdoor plays (RHO: 0.37, p =0.0009) and practicing of sports (RHO: 0.33, p =0.003). Obese children were less active than non obese children, according both to PA score and to accelerometry. The optimal cut-point for classifying a child as too sedentary was a score of 5 (sensitivity =0.89). Conclusions: The INTA-test is a valuable instrument for measuring usual PA in clinical practice and is easy to administer (