Asymmetric dimethylarginine (ADMA) is the main endogenous inhibitor of nitric oxide synthase and is considered to be associated with endothelial dysfunction. Brucellosis, a zoonotic disease caused by Brucella spp., can manifest as vasculopathy. The present study was performed to investigate the relationship between ADMA and brucellosis. Serum samples from 39 patients with an accurate diagnosis of brucellosis and from 18 healthy control individuals were included in this study. ADMA levels were significantly higher in the patient group than the controls (P < 0.001). Receiver operating characteristic (ROC) curve analysis indicated that ADMA level ≥ 0.61 had a sensitivity of 79.5 %, specificity of 88.9 %, positive predictive value of 93.9 %, and negative predictive value of 66.7 %. This is the first report of an association between brucellosis and high levels of ADMA. In conclusion, ADMA levels should be tested in brucellosis cases and that further studies to clarify the mechanism underlying the association between ADMA and brucellosis are required.