Pulmonary function tests were conducted in 60 male adults and 60 female adults at 20~79 years of age. They showed noevidenee of pulmonary disease on clinical symptoms, X-ray finidngs and past history. We wanted to evaluate the deterioration of pulmonary functional reserve in the aged. The results were as follows: 1) In males, FVC decreased significantly (p <0.01) from 4440±271.38 ml in 20~29 year-old subjects to 3090±445.75 ml 70~79 year-old subjects. The correlation coefficient with age was-0.6846. 2) In females, FVC decreased significantly (p<0.01) from 2097±479.42ml in 20~29 year-old subjects to 2142±233.13ml in 70~79 year-old subjects The correlation coefficient woth age was 0.6454. 3) In males, FEV, decreased significantly (p<0.01) from 4005±268.26 ml in 20~29 year-old subjects to 2373±326.36ml in 10~79 year-old subjects. The correlation coefficient with age was-0.8229. 4) In females, FEV1 decreased significantly (p<0.01) from 2586±519.00 ml in 20~29 yrar-old subjects to 1645±330.36ml in 70~79 year old subjects The correlation coefficient with age was 0.7013. 5) In males, FEV1/FVC decreased significantly (p<0.01) from 90.17±4.90% in 20~29 year-old subjects to 76.72±8.13% in 70~79 year-old subjects. The correlation coefficient with age was-0.5595. 6) In females, FEV1/FVC decreased significantly (p<0.01) from 88.66±6.58% in 20-29 year-old subjects to 76.80±9.32% in 70~79 year-old subjects. The correlation coefficient with age wae-0.4489.