['To investigate the prevalence of metabolic syndrome (MS) in patients with lupus nephritis (LN), and its correlation with carotid atherosclerosis.', 'Two hundred ten patients with LN (age: 38.83 ± 12.41 years, 92.86% women) were enrolled. The control group included 150 lupus patients without nephritis and 200 age-matched healthy persons. The improved criteria in 2009 were used to calculate the prevalence of MS, and carotid artery ultrasound was used to detect plaque and intima-media thickness (IMT). The correlation between MS and carotid atherosclerosis in patients with LN was analyzed.', 'The prevalence of MS in patients with LN was 41.90%, which was significantly higher than that in lupus patients without nephritis (30.67%) and healthy controls (11.50%). LN patients with MS showed a significantly increased carotid plaque ratio (28.41% versus 17.21%, P < 0.05) and IMT value (0.74 ± 0.25 mm versus 0.64 ± 0.18 mm, P < 0.01). Stepwise multiple regression further confirmed that age (β = 0.026, P = 0.033), duration of disease (β = 0.057, P = 0.025) and MS (β = 0.074, P < 0.001) were independent risk factors that affected the carotid IMT value in patients with LN.'] Is metabolic syndrome correlated with carotid atherosclerosis in patients with lupus nephritis?