Objectives Circulating levels of asymmetric dimethylarginine (ADMA), an endogenous nitric oxide synthase inhibitor, are increased in hypertensive patients. This study was to assess the relationship between plasma ADMA level and carotid atherosclerosis in patients with essential hypertension.

Methods A total of 182 individuals with never-treated essential hypertension and 182 age-matched healthy controls were studied. All study subjects were examined by B-mode ultrasound to measure the intima–media thickness (IMT) and plaque score in the carotid artery.

Results Plasma ADMA levels, mean IMT, and plaque score were significantly greater in hypertensive patients than normotensive controls. In all subjects, plasma ADMA was positively correlated with mean IMT (r = 0.44, p < 0.001). On multiple logistic regression analysis, ADMA was a crucial independent predictor of carotid plaque formation (plaque score ≥ 1.1) (odds ratio 2.06, 95% confidence interval 1.49 to 2.85, p < 0.001).

Conclusions Our results suggest that increased levels of ADMA are associated with the development of carotid atherosclerosis in hypertensive patients.