Several factors which influence the balance between fibrinolysis and coagulation pathways play role in the outcome of conception. A large body of studies demonstrate that gene variations are associated with recurrent pregnancy loss (RPL) by different mechanisms. We aimed to determine the allele and genotype frequencies of the angiotensin converting enzyme (ACE) gene in Iranian Azeri Turkish women with unexplained RPL. Fifty patients with RPL and 63 fertile healthy women as controls were entered in the study. A standard method was used for DNA isolation. All genotypes were determined using PCR. Our analysis showed that patient (chi(2) = 0.347, p = 0.84) and control (chi(2) = 0.77, p = 0.68) groups fitted the Hardy-Weinberg equilibrium strongly. No significant differences were found regarding the frequencies of ACE genotypes [deletion/deletion (D/D), insertion/deletion (I/D) and insertion/insertion (I/I)] and alleles between cases and controls. Based on these findings, we could not find any association between ACE (D/D, I/D and I/I) gene polymorphisms and RPL.