Interoduction: The tumor suppressor gene P53 play general role in cell cycle control, the initiation of apoptosis and in DNA repair. The human P53 gene is mutated and accumulated in more than 50% of cancers. Codon 72 exon 4 polymorphism (Arg72Pro) of the P53 gene has been implicated in cancer risk. Our objective was to investigate the possible association between P53 Arg72Pro polymorphism and susceptibility to breast cancer among Isfahan and Charmahal Va Bakhtiari (a part of Iran) population.Methods: the P53 Arg72Pro genotypes were determined by PCR-based restriction fragment length polymorphism (PCR-RFLP) analysis in 85 breast cancer cases and 50 controls. The PCR products were digested with BstUI restriction enzyme and the DNA fragments were then resolved by electrophoresis in 2% agarose gel.Result: Of the 85 breast cancer samples, 63 (74.11%) samples were heterozygous (Arg/Pro), 17 (20%) samples homozygous for arginine (Arg/Arge) and 5 (5.88%) samples homozygous for praline (Pro/Pro). The frequencies of the three P53 genotypes; Arg/Pro, Arg/Arge and Pro/Pro in controls were 62%, 24% and 14%, respectively.Discussion: Hetrozygosity for Arg/Pro of P53 codon 72 is potentially one of the genetic risk factors for breast cancer. The p53 Arg72Pro polymorphism may be used as a stratification marker in screening individuals at a high risk of breast cancer.