Objective To explore the relationship of carotid atherosclerosis with serum level of oxidized low-density lipoprotein (ox-LDL) and atherogenic index of plasma (AIP) in patients with acute cerebral infarction (ACI).Methods One hundred and twenty patients with ACI were consecutively enrolled as subjects. Sixty healthy people within the same period were used as controls. The level of ox-LDL, plasma lipid metabolism, and AIP were evaluated in the two groups. The plasma lipid metabolism was characterized with the levels of triglycerides (TG), low-density lipoprotein (LDL-C), and high-density lipoprotein (HDL-C). The ACI group was divided into normal carotid intima-media thickness (IMT) group (n=11), large IMT group (n=25), and carotid atherosclerosis (CAS) group (n=84) according to the results of carotid artery sonography. The level of ox-LDL and AIP were compared between the three groups.Results Compared with the control group, the ACI group had significantly higher detection rates of plaque and vulnerable plaque, a significantly higher level of ox-LDL, and a significantly higher AIP (all P<0.01). In patients with ACI, the CAS group had significantly higher serum level of ox-LDL and AIP than the large IMT group (all P<0.01), while the large IMT group had significantly higher serum level of ox-LDL and AIP than the normal IMT group (P < 0.01, P < 0.05). The Pearson analysis showed that IMT was positively correlated with the ox-LDL level and AIP (r=0.720, P<0.01; r=0.708, P<0.01), while the ox-LDL level was correlated with AIP (r=0.655, P<0.01).Conclusions ox-LDL and AIP are closely related to the formation and development of CAS and the incidence of ACI. The combined measurement of the two indices provides a comprehensive assessment of the risk of ischemic stroke.