The aim of this study was to evaluate the predicted values of pack expiratory flow for the Polish children and youth by means of measures Mini Wright and Personal Best. The accounts were based on a group of 86 boys and 110 girls. It was established that it was necessary to state different predicted values for different measures and that an optimum model of regression for counting of predicted values of PEFR in relation to body height for the Polish children and youth was an exponential model. Model indices for both measures were set up separately for boys and girls.