The study was conducted on 474 children diagnosed at the Lung Function Laboratory of the Children' Hospital in Lublin in the year 1992. 55% of the analyzed children were males. The children's initial diagnosis were: bronchial asthma, allergic rhinitis, chronic respiratory disorders, diabetes mellitus, abnormalities of the thorax. In 28 children no abnormalities were detected. PEF was measured with a Peak Flow Meter produced by Vitalograph. Children in the age group 4-6 years had PEF measured with a mini meter, reading values between 0 to 300 L/min. A standard meter was used for older children detecting values between 0 to 700 L/min. Spirometry, MEFV curves, resistance were analyzed with the abcPNEUMO 2000 spirometer (abcMED). Correlation was calculated between PEF and FEV1, MEF25, MEF50, MEF75, PEF, PIF, FEV1%FVC, Raw. Multiple regression analysis was performed to identify the best subpopulation of independent variants. In all children a correlation was found between PEF and the major parameters of airways potency. The weakest correlation was found in children younger than 6 years. PEF correlated best with FEV1 and MEF75.