Aim To investigate the insulin receptor substrate 1 (IRS 1) gene polymorphism and its relationship with serum lipids and apolipoproteins (Apo) levels in patients with endogenous hypertriglyceridemia (HTG) in Chinese population. Methods The genotype and allele frequency of IRS 1 gene polymorphism was assayed by polymerase chain reaction (PCR) restriction fragment length polymorphism (RFLP). Serum lipids were measured by enzymatic kits and apolipoproteins A_Ⅰ, A_Ⅱ, B₁₀₀, CⅡ, CⅢ and E by RID kits developed by Apolipoprotein Research Unit of WCUMS in 117 HTG patients whose fasting serum TG levels were ≥2.26 mmol/L and 194 healthy subjects whose fasting serum TG levels were <1.82 mmol/L and TC levels <6.2 mmol/L from a population of Chinese Han nationality in Chengdu area. Results Both in HTG group and control group, the GG genotype of IRS 1 gene was the major one, and its frequency was 0.995 and 0.985 respectively. In the HTG group, subjects with the genotype GR had a lower serum ApoCⅢ levels than those with the genotype GG (p>0.05). Conclusion These results suggest that the IRS 1 gene G 972 R polymorphism was not associated with endogenous hypertriglyceridemia in Chinese population.