Elderly patients with chronic obstructive pulmonary disease may be at increased risk of exacerbation due to physical and cognitive deficits that make proper inhaled medication adherence more difficult despite consistent medication access. This retrospective study utilized administrative medical and pharmacy claims data to examine the likelihood of having a COPD exacerbation requiring acute medical care by means of an emergency room visit or hospitalization in elderly patients receiving maintenance COPD medications from mail order and retail pharmacies. It was hypothesized that mail order patients would be more likely to experience exacerbations despite differences in medication access when compared to retail patients. The primary outcome of interest was exacerbation frequency expressed as the incidence density rate, and the secondary outcome was the proportion of days covered (PDC). The incidence rate ratio for acute exacerbations was not significantly different for mail order and retail groups, indicating patients using mail-order pharmacies were not significantly more likely to experience an exacerbation requiring acute medical care. Despite insignificant differences in incidence rates, mail order patients had significantly higher adherence rates.