IntroductionAsymmetric dimethylarginine (ADMA) and nitric oxide (NO) show their mechanism of action reciprocally, the balance between these molecules contributes to the tight regulation of airways tone and function. ObjectivesThe aim of this study to determine the serum levels of ADMA and NO in patients with chronic obstructive pulmonary disease (COPD) and establish whether their level vary in relation to forced expiratory volume in 1s (FEV1), to assess their role in pathophysiology of COPD. Materials and MethodsThis study consisted of 58 patients with COPD and 30 healthy subjects. Serum ADMA and NO levels were measured using enzyme-linked immunosorbent assay and the colorimetric method, respectively. ResultsSerum ADMA levels were significantly higher, however, NO levels were lower in patients with COPD compared with controls. ADMA levels were inversely correlated with NO levels. Serum ADMA and NO were significantly correlated with FEV1. Multivariable logistic regression analysis revealed that serum ADMA and NO were independently and significantly associated with the presence of COPD. Multiple linear regression analysis showed that COPD was positively associated with ADMA, additionally COPD and ADMA were independently and inversely associated with NO. NO levels were decreased, ADMA levels were increased compliant with progression of COPD stages. ConclusionWhile circulating ADMA is higher, NO is lower in COPD and both show a strong correlation to the degree of airflow limitation. ADMA seems to be a possible new marker of prognosis of COPD and can be a novel therapeutic target for the treatment of COPD.