Background: To examine the individual effect of elevated homocysteine and its combined effect with hypertension on early carotid artery atherosclerosis (ECAS). Methods: We recruited 1257 subjects from a community-based population in Beijing, China, aged 55 years and older. The definition of hyperhomocysteinemia was referred to as the presence of homocysteine concentrations greater than 15 mu mol/L. Carotid intima-media thickness (CIMT), plaque, the sum of plaque thickness (plaque score, PS), and plaque location in common carotid artery were established by ultrasonography. The presence of increased CIMT (>= 1.0 mm) and plaque was defined as ECAS. Age, sex, smoking, alcohol drinking, physical activity, total cholesterol, glucose, estimated glomerular filtration rate, hypoglycemic therapy, and lipid-lowering therapy were adjusted by logistic regression analysis. Results: After adjustments for all potential confounders, the risks of presence of plaque, bilateral plaque, and high PS were significantly higher in the group with hyperhomocysteinemia as compared with reference group (the normal homocysteine and normotensive). The odds ratios (ORs) were 1.56 for presence of plaque (95% CI 1.05-2.33), 1.80 for bilateral plaque (95% CI 1.08-2.99), and 1.90 for high PS (95% CI 1.09-3.30), respectively. The group with both hyperhomocysteinemia and hypertension manifested the highest ORs of ECAS. The fully adjusted ORs were 1.67 for increased CIMT (95% CI 1.15-2.42), 2.48 for bilateral plaques (95% CI 1.54-3.99), and 2.69 for high PS (95% CI 1.61-4.47), correspondingly. Conclusions: Elevated homocysteine had a mild-to-moderate independent effect on ECAS. Combined with hypertension, hyperhomocysteinemia might increase the strength of the above-mentioned effects. (C) 2016 National Stroke Association. Published by Elsevier Inc. All rights reserved.