Background and objectives: Metabolic syndrome (MetS) is a cluster of the most dangerous risk factors for type 2 diabetes mellitus and cardiovascular disease (CVD). The -1131T/C is a naturally occurring variant of the apolipoprotein A5 (APOA5) gene, which has been shown to associate with Hypertriglyceridaemia and correlate with impaired glucose homeostasis. These observations prompted us to explore the frequency of APOA5 1131T/C polymorphism among patients with MetS and to assess its effects on lipid metabolism and insulin resistance.Patients and Methods: The study was conducted on 90 subjects divided into 2 groups: 60 MetS patients and 30 healthy controls. Fasting glucose, lipid profile, C-peptide (by ELISA method to calculate modified HOMA-IR) and APOA5 1131T/C polymorphism (PCR-RFLP) were done to all participantsResults: The homozygous variant (CC) of APOA5 gene was present only in MetS group compared to controls with a frequency of 13.3% vs 0 %( P=0.011), while the wild genotype (TT) was more frequent among the controls (86.7% vs 56.7%, P=0.011). The mutant genotypes (TC,CC) were associated with higher risk for MetS (OR 4.97). The C allele was significantly increased in cases compared to controls (28.3% vs. 6.7%. P= 0.001) and was associated with increased risk of MetS, OR=5.535. Cholesterol, triglycerides, HDL, glucose levels and modified HOMA-IR showed significantly higher values in the TC/CC genotypes compared to TT genotype among MetS patients.Conclusions: Our findings strongly suggest that APOA5 gene T1131C polymorphism is associated with a higher risk for MetS, and C allele carriers (TC/CC) are more susceptible to dyslipidemia and insulin resistance among those patients.