Study objectives: Inhaled corticosteroids (ICS) are widely used in the treatment of COPD. One of the potential adverse effects of their use is the development of adrenal suppression. Our study aimed to determine the effects of ICS on adrenal function over 3 years of use in patients with COPD. Methods: Two hundred twenty-one subjects were recruited from the 1,116 patients already enrolled in Lung Health Study II and were randomized to receive either triamcinolone, 1,200 μg, or placebo daily. Basal cortisol levels and cortisol levels at 30 min and 60 min following cosyntropin injection were measured at study entry and after 1 year and 3 years of participation. Results: Basal cortisol levels in the placebo group were higher than in those receiving active drug at all time points and rose through the study period. There was no suppression of cortisol levels after cosyntropin stimulation at any study point in any subgroup. Conclusion: Use of inhaled triamcinolone, 1,200 μg/d, over 3 years does not suppress baseline adrenal function or diminish adrenal responsiveness to cosyntropin stimulation.