It is important to establish lung function reference values for each population. This study aimed to determine the spirometric reference values for healthy Saudi Arabian children and adolescents and to derive prediction equations for these. A cross-sectional study was conducted among healthy schoolboys and girls aged 6-18 years old, selected randomly from the 6 administrative regions of Saudi Arabia. Data were collected by questionnaire and physical examinations including spirometry. Forced

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... ratory volume in 1 second (FEV1) and forced vital capacity (FVC) were significantly higher in males than females. Height was the anthropometric variable most strongly correlated with FEV1 (r = 0. 61), more so for males (r = 0.71) than females (r = 0.50). In males the multivariate linear regression model explained 53.9% of FEV1 and 35.1% of FVC variations. In females it explained 25.3% of FEV1 and 16.5% of FVC variations. All changes in R² were statistically significant.