Objective To investigate the association between the serum level of retinol-binding protein (RBP) and carotid atherosclerotic plaque in patients with acute cerebral infarction (ACI).Methods A total of 96 ACI patients (ACI group) and 95 normal controls (control group) were enrolled and the serum level of RBP was measured.The levels of serum uric acid (UA),plasma D-dimer (DD),and fibrinogen (FIB) were also measured.According to the results of carotid artery ultrasound,the ACI patients were further divided into non-plaque subgroup (41 patients),stable carotid plaque subgroup (28 patients),and unstable carotid plaque subgroup (27 patients),and the serum level of RBP was compared between the three groups.Results The ACI group had a significantly higher serum level of RBP than the control group (P<0.05).In the ACI group,the stable and unstable carotid plaque subgroups had a significant increase in the serum level of RBP compared with the non-plaque subgroup (both P<0.05),and the unstable carotid plaque subgroup had a significantly higher serum level of RBP than the stable carotid plaque subgroup (P<0.05).The linear correlation analysis showed that RBP level was not significantly correlated with the levels of UA,DD,and FIB (r=0.192,0.088,and 0.096,all P>0.05).The logistic regression analysis showed that RBP was a risk factor for the development of carotid atherosclerotic plaque (odds ratio=2.769,95% confidence interval 0.007-0.722).Conclusions Serum RBP may be an important marker for atherosclerosis and might be closely associated with the stability of atherosclerotic plaques in patients with ACI.