Studies on pallid mice models of genetic emphysema have conventionally focused on morphological or biochemical evaluations. However, it is important to consider the functional aspects. We evaluated the exercise capacity and respiratory function in male pallid mice and male C57BL/6J mice at 3, 6, 12, and 15 months of age. The functional evaluations were conducted using a treadmill and a pulmonary function analysis device. The morphology of the lungs was analyzed on the basis of mean linear intercept (Lm) values. The body weights of the pallid mice at 12 and 15 months were significantly lower than those of the age-matched C57BL/6J mice. The pallid mice showed deterioration in exercise capacity from 6 months, as indicated by the trends in running distance. At 6, 12, and 15 months, the pallid mice showed significantly higher pulmonary compliance and significantly lower forced expiratory volume in 20 ms (FEV(20 ms))/vital capacity (VC) values in comparison with the corresponding values for the C57BL/6J mice. In the morphological analysis of the pallid mice, emphysema was detected from 12 months, and the mice showed a significantly larger Lm at 12 months. The exercise capacity and lung function in the pallid mice significantly deteriorated from 6 months, at which time no pathological changes in the lung were detected. The deterioration in the exercise capacity and pulmonary function preceded the microscopic morphological changes. Laboratory Investigation (2009) 89, 760-768; doi:10.1038/labinvest.2009.34; published online 20 April 2009