Objective To investigate effects of apolipoprotein (apo) E polymorphism on serum apoA1 and apoB levels in Maonan ethnic group. Methods Serum apoA1 and apoB concentrations were measured in 221 healthy subjects from a population of Maonan ethnic group in Qiannan autonomous area of Guizhou province using immunoturbidimetric assay. ApoE2,E3,E4 genotypes were determined by polymerase chain reactionrestriction fragment length polymorphisms (PCR-RFLPs). Results Increased apoB levels and decreased apoA1-to-apoB ratio were found in carriers with apoE4 isoform (E3/4+E4/4) ( n =41) and apoE3/3 homozygotes ( n =143) as compared to carriers with apoE2 isoform (E2/2+E2/3+ E2/4) ( n =37, P <0.05). ApoB levels were higher in carriers with apoE4 isoform than those with apoE3/3 homozygotes ( P <0.05). No significant differences were found for apoA1 levels among the groups mentioned above ( P >0.05). Conclusion This study suggests that apoE polymorphism is associated with serum apoB levels and apoA1/B ratio, but not with apoA1 levels, in Maonan e