PurposeChronic obstructive pulmonary disease (COPD) is accompanied by increased inflammation, persistent lung function decline, and extensive lung injury. Klotho, a well-known antiaging protein, has anti-inflammatory and antioxidative effects. However, the effects of klotho on COPD have yet to be thoroughly elucidated. This study examined the association among COPD adults and their α-klotho level.Patients and methodsData were collected from the 2007 to 2012 National Health and Nutrition Examination Survey (NHANES). A total of 676 participants were analyzed and divided into COPD (n = 403) and non-COPD (n = 273) groups. The two groups were compared with respect to clinical characteristics. Logistic regression analysis and a generalized additive model were used to estimate the association between COPD incidence and serum α-klotho concentration. All COPD participants were stratified according to the levels of α-klotho (Q1: