We looked for germline mutations of exons 5 to 8 of the P53 gene in 27 female patients from 26 families originating from the north of France who had breast cancer and at least one first degree relative also affected with breast cancer. Detection of the mutations was made by single strand conformation polymorphism analysis. No mutation was found in any patient, confirming that germline mutations of the P53 gene are very rare in familial breast cancer (apart from Li Fraumeni families).