Conclusion. While the pulmonary function predictions obtained with the three sets of indices are similar, different threshold values for categories definitions need to be used for direct comparisons between charts.Objective. To compare Forced Expiratory Volume in 1 second (FEV1) predictions calculated with different growth indices in pediatric patients with Cystic Fibrosis (CF).Results. The indices based on the three charts predict similarly the pulmonary function. The FEV 1 calculated using the 2000CDC indices are the closest to the observed values.Methods. Anthropometric and pulmonary function measurements, demographics and bacteriology data were retrospectively collected from the CF database at The Hospital for Sick Children on a 10 year birth cohort of 103 pediatric patients. A multiple regression model was developed using growth indices based on the 2000CDC reference charts to predict the FEV1. The predictions were then compared with the ones calculated with equivalent models using the Tanner and NCHS charts.