The relation between mold to moderate emphysema and lung function tests, including tests reported to identify "early" or mild disease, were examined using 24 excised human lungs, 5 with no emphysema, 11 with grade 5 or less emphysema, and 8 with as much as grade 50 emphysema. Static pressure volume curves, single breath nitrogen (SBN2) tests, maximal exemphysema. Static pressure volume curves, single breath nitrogen (SBN2) tests, maximal expiratory flow volume (MEFV) curves with air and a mixture of 80% He and 20% O22, and forced expiratory volume in one second (FEV1) were measured in all lungs. Negative correlations were found (r - -0.489, p less than 0.02) between the emphysema grade and the per cent predicted static lung recoil at 50% of total lung capacity and the emphysema grade and the per cent predicted FEV1 (r = 0.428, p less than 0.05). There was no significant correlation between the grade of emphysema and the SBN2, or MEFV test. Negative correlations were found between the elastic recoil, expressed as per cent predicted slope of Phase III (r = 0.482 p less than 0.02), and the per cent predicted FEV1 (r = -0.619, p less than 0.01). We concluded that mild to moderate degrees of emphysema are not correlated with single breath nitrogen test or flow volume curves using air or helium, but are better related to loss of elastic recoil in excised human lungs.