The p53 gene is one of the most extensively studied human genes because of its role as a tumor suppressor gene. Its diverse functions include DNA binding, cell cycle control, DNA repair, differentiation, genomic plasticity, and apoptosis. A common polymorphism of the p53 gene at codon 72 has been associated with human cancer susceptibility and prognosis. In this study, we investigated p53 codon 72 polymorphism in 42 breast cancer cases and 60 healthy individual in northern Iran. Genomic DNA was extracted from fresh tumor tissues of patients and blood samples of healthy individuals. AS-PCR method was applied for determination of codon 72 polymorphism. The distribution of genotypes in breast cancer cases and controls were different (p = 0.001). Pro allele was significantly associated with the presence of breast cancer (odds ratio = 1.5 and 95% confidence interval = 0.85-2.63). Pro/Pro genotype was overrepresented in breast cancer. Based on these data, it is suggested that Pro allele may modify the risk of breast cancer in northern Iranian women.