BACKGROUND: Cowden's disease is a rare disorder, characterized by a multiple harmatoma-neoplasia syndrome. Germline mutations in the Phosphatase and Tensin homolog (PTEN) gene have been identified in some individuals with Cowden's disease. The present study aimed to evaluate abnormalities of PTEN and p53 genes in a patient with Cowden's disease. METHODS: Eleven family members including the patient with Cowden's disease were examined in this study. Sequencing analyses were performed on these people and on the normal control group to identify mutation in PTEN and p53 genes. RESULTS: DNA sequencing of PTEN gene showed no mutation in the patient and the family members. The G to C germline mutation was identified only in the patient of Cowden disease at 38th base of intron 2 of p53 gene. CONCLUSIONS: Although the exact role of mutation in p53 gene was not identified in the Cowden's disease, the conformational change of the gene would result in the dysfunction of the tumor suppressor effect of p53 gene. Otherwise, an epigenetic silencing can be a mechanism of disease development in a patient without genetic abnormality.