The normal values of pulmonary ventilatory function were obtained using a computerized hot-wire spirometer in 516 healthy children aged 6,9 and 12 years. Forced vital capacity (FVC), forced expiratory volume in one second (FEV1) and FEV1/FVC ratio were analyzed. Regression equations of FVC and FEV1 against height could be separated at 140cm. They were as follows : lower than 140cm; FVC=0.0397X___--3.301 and FEV1=0.0327X___--2.613 for boys, FVC=0.0325X___--2.538 and FEV1=0.0290X___--2.240 for girls; higher than 140cm; FVC=0.0556X___--5.511 and FEV1=0.0469X___--4.561 for boys, FVC=0.0538X___--5.358 and FEV1=0.0448X___--4.299 for girls, where FVC and FEV1 are in liters and X___- is height (cm). The mean values of the FEV1/FVC ratio of children aged 6,9 and 12 years were 91.2%, 88.5% and 87.6% in boys and 90.6%, 89.1% and 89.5% in girls, respectively.