ETNIER, J. L., and M. BERRY. Fluid intelligence in an older COPD sample after short- or long-term exercise. Med. Sci. Sports Exerc., Vol. 33, No. 10, 2001, pp. 1620–1628. Purpose: Research supports an association between aerobic fitness and cognitive functioning in chronic obstructive pulmonary disease (COPD) patients. However, the impact of exercise intervention duration has not been satisfactorily examined. Therefore, the purpose of this study was to examine the effects of a 3-month and an 18-month exercise intervention on the cognitive functioning of an older COPD sample. Methods: COPD patients (56–80 yr) were given a 3-month exercise program and then were randomly assigned to continue for an additional 15 months (long-term group) or to leave the exercise program (short-term group). Age and education were assessed before involvement in the exercise intervention (baseline). Fluid intelligence, pulmonary function, aerobic fitness, and depression were assessed at baseline, at 3 months, and at 18 months. Results: After 3 months of exercise, results indicated that cognitive function and walk distance improved significantly. Results also indicated that the gain in cognitive function was reliably predicted by the decrease in V̇E at V̇O2peak. At 18 months, results indicated that cognitive performance did not differ between the short- and long-term exercise groups, but that walk distance improved significantly for the long-term group, but not for the short-term group. Results of a regression analysis showed that the cognitive performance improvement from 3 months to 18 months was predicted by the gain in walk distance and by the decrease in V̇E at V̇O2peak. Conclusion: It is concluded that improvements in aerobic fitness are associated with gains in fluid intelligence after 3 and 18 months of exercise training in COPD patients. However, at 18 months, exercise group was not predictive of the gains in cognitive performance. Therefore, a 3-month exercise program may be a sufficient impetus to foster these cognitive gains in COPD patients.