We measured the PEFV curves in 557 adolescents aged from 6 to 19. Among them 200 were measured for MEFV curves additionally. The multiple regression equations of FVC and VFRC were simultaneously set up. The result indicated that the indexes increased with the growth of age. At the beginning stage (6-14 years) there was no difference in the indexes between boys and girls. Later in the age range from 14-16 years there were two cross points. Lastly (after 16 years) the indexes of the boys were much higher than those of the girls. The results suggest that the measurement of VFRC is a possible sensitive index to reflect the lung function variation, because it has not been influenced by the volume history.