We have shown previously, using the technique of magnitude estimation, that the change in sensation level for a given change in elastic loading is less in elderly than in young subjects. In the present study, we used the same technique to compare the perception of added inspiratory and expiratory resistive loads in 40 young (18 to 30 yr of age) and 19 elderly (60 yr of age and older) subjects. Two different ranges of loads were studied and the relation between load magnitude and sensation intensity (the exponent for magnitude estimation) was determined. The study showed that the exponent for both inspiratory and expiratory loads is less in the older group. Because peak airway pressure and the inspiratory and expiratory times while breathing against the added loads were the same in both age groups, the difference in exponents in the two groups was not caused by differences in the forces generated during breathing. Age-related changes in sensory perception may affect behavioral responses to impaired respiratory mechanics.