Objective: Angiotensin converting enzyme (ACE) catalyses the conversion of angiotensin I to angiotensin II, which increases the PAI-1 plasma level. The insertion/ deletion (I/D) polymorphism in intron 16 of the ACE gene is associated with the ACE expression. Homozygosity for the D allele of the ACE gene, which results in elevated PAI-1 concentrations and hypofibrinolysis, is related with an elevated risk of thrombophilic diseases such as pulmonary thromboembolism, deep venous thrombosis, and pregnancy outcome. Materials and Methods: We aimed to assess the association between polymorphism in the ACE gene and pulmonary thromboembolism by a case-control study in North West of Iran. DNA was extracted from peripheral blood leukocytes of 53 PTE patients and 32 controls. Genotyping of (I/D) ACE polymorphism were carried out by ARMS-PCR method. Results: The ACE polymorphisms of the 53 patients identified that 23% had I/I genotype, 46%were I/D and 31% were D/D. Among the 32 controls 19% had I/I genotype, 50% were I/D and 31% had D/D genotype. Conclusion: In conclusion, our results demonstrate that no statistically significant differences in the prevalence of this polymorphism. Although (I/D) ACE polymorphism has no role in the etiology of PTE, the data should be verified with the aid of a larger population.