【Abstract】 Objective To investigate effects of apolipoprotein A5 apoA5) gene-1131T＞C polymorphism on serum lipid and apolipoprotein levels in obese subjects from a population of Chinese Han nationality in Chengdu. Methods 102 obese patients and 193 nonobese subjects were studied using the polymerase chain reactionrestriction fragment length polymorphism (PCR-RFLP). Triglyceride (TG), total cholesterol (TC) and high density lipoprotein cholesterol (HDL-C) were measured by enzymatic kits and apolipoproteins AI, AII, B100, CII, CIII and E were measured by the RID kits. Results The allele frequencies of T and C were 0.676 and 0.324 in obese group, and 0.687 and 0.313 in control group, respectively. There were no significant differences of genotype and allele frequencies between the two groups (P＞0.05). In control group, subjects with CC genotype was associated with significantly higher serum triglycerides, levels and TG/HDL-C ratio and lower HDL-C levels, when compared with those with the TT or TC genotypes. In obese group, subjects with CC genotype was associated with higher TG and TG/HDL-C, and lower low density lipoprotein cholesterol (LDL-C) level when compared with those with genotype TT (P＜0.05). In addition, in non-obese group subjects with CC genotype showed higher apoC-Ⅱ、C-Ⅲ and E-levels when compared to those with TT or CC genotype. In obese group subject with CC genotype showed lower apoB levels, when compared to those with TT or TC genotype. Conclusion There was no correlation between APOA5 gene 1131T>C polymorphism and obesity. The polymorphism of APOA5 gene 1131T > C is related to the increase of serum TG level and TG / HDL-C ratio in non obese and obese patients, and is related to the change of some serum apolipoproteins.