© 2015 Mary Ann Liebert, Inc.Aim: This study was performed on primary hypertension patients in a Turkish population to determine the frequency of the A1166C polymorphism in the angiotensin II type 1 receptor (AT1) gene and to examine the role of this polymorphism in hypertension development.Materials and Methods: In this study, 250 genomic DNA samples were collected (from 142 hypertension patients and 108 healthy subjects), randomized, and analyzed. Genomic DNA was prepared from peripheral blood using the salt extraction method. The presence of the A1166C polymorphism in the AT1 gene was determined using the polymerase chain reaction (PCR)-restriction fragment length polymorphism method. PCR products were separated by 2% agarose gel electrophoresis and visualized by a charge-coupled device camera.Results: Genotype distribution and allele frequency A1166C genotype frequency was determined as AA 96.3% and AC 3.7% for controls and as AA 86.6% and AC 13.4% for patients. A statistically significant difference was found between the control group and patients in terms of genotype and allele frequency.Conclusion: Our results suggest that an interaction exists between the AT1 gene polymorphism and hypertension in the Turkish population.