The recent isolated gene BRCA2 is responsible for about 45% of familial breast cancer and the majority of male breast cancer families. In order to evaluate the role of inherited BRCA2 mutations in Spanish families, the complete coding sequence of the gene was screened by SSCP/sequencing in 16 high-risk breast/ovarian cancer families. Four mutations were found that cause a premature termination codon. Two of them have been reported elsewhere and one is a novel mutation. In addition we have found seven polymorphisms, two of which have not been previously described. One of the mutations, 936delAAAC was found in two of our high-risk families. Because this mutation is considered as recurrent, we have tried to estimate its frequency in our breast cancer population. A total of 127 moderate- high-risk families were screened for this mutation and it was also found in another high-risk family. All the families carrying the 936delAAAC mutation harboured part of a common haplotype shared by other reported carriers, suggesting a possible founder effect for this mutation.