Standard values of pulmonary ventilatory capacity were measured for boys and girls between 12 and 19 yeas of age by means of the Vitalor, which is useful for determining Forced Vital Capacity (FVC), Forced Expiratory Volume (FEV_<1.0>) and Maximal Expiratory Flow Rate (MEFR). Results obtained are as follows: 1) FVCs of the boys were greater than those of the girls. FVCs of the boys showed an abrupt increase between the ages of 12 and 14, but the increase rate was diminished after the age of 14. Meanwhile, FVCs of the girls also showed a tendency of increase between 12 and 15, but the increase rate for the girls was lower than that for the boys, and no increase was recognized for the girls older than 15. 2) FEV_<1.0> show the same tendency as FVC. However, diminution was recognized for the girls of 19 when compared with the girls of 15. 3) The same tendency was observed on MEFR, but MEFR of the girls showed decrease in earlier age than that of the boys.