sRaw is independent of height and gender,5,29–30 facilitating the interpretation of measurements carried out longitudinally in individual children. We reported measurements of sRaw in 121 healthy 2- to 7-year-old white children (61 boys and 60 girls), with approximately 20 youngsters at each year of age. The participants in this study had no history of recurrent lower respiratory symptoms, no history of eczema and no atopic first-degree relatives, no significant exposure to tobacco smoke, and no history of respiratory symptoms during 1 month prior to the examination of lung function. The reference value for sRawtot was 1.3 kPa/s and 1.1 kPa/s for sRawV̇max. Neither measurement of sRaw showed any significant correlation with gender, age, weight, or height.,10 Other studies5,29–30 have reported values of sRawV̇max ranging from 0.45 to 1.0 kPa/s. The difference is probably due to the use of electronic BTPS compensation in the former study and heated rebreathing system in the latter.