The purpose of this study was to find out the effect of the ApoE genotype on the relationship between metabolic syndrome (MS) and its diagnostic components and cognitive impairment in the elderly. A total of 2944 subjects aged over 60 years were analyzed from the data of Gwangju Dementia and Mild Cognitive Impairment Study. We examined demographic characteristics, current and past illness history, drug history, Korean version-mini-mental state examination (K-MMSE). We also examined ApoE genotype and analyzed associated factors with MS. The MS was present in 53.8% of the subjects (36.8% of men and 61.1% of women). On multiple logistic regression analysis, MS was not associated with the cognitive impairment (K-MMSE score <18) adjusted for age, sex, and educational level. The interactive effect between systolic and diastolic blood pressure (SBP, and DBP, respectively) and ApoE on cognition was not significant (all p>0.3), but the interactive effect between triglyceride (TG), high-density-lipoprotein-cholesterol (HDLc) and ApoE on cognition was significant after adjustment for age, sex, and education (B=-0.285, Wald=4.194, p=0.041; B=0.372, Wald=4.134, p=0.042). These results suggest that blood TG and HDLc may affect cognitive function in the elderly in the presence of ApoE varepsilon4 allele.