This report describes a commercial laboratory's novel approach to providing genetic testing services to detect BRCA1 mutations in persons with hereditary breast/ovarian cancer. The approach involves the use of institutional review board (IRB)-approved protocols as a paradigm for conducting genetic testing in a commercial setting. We discuss the rationale for this approach and the key elements of the protocol. In addition, we provide data on the first 6 months of implementation of the protocol in 32 clinical sites. A phased testing approach was used, consisting of an allele-specific oligonucleotide assay for the 8 most common BRCA1 mutations, a protein truncation test of exon 11, and direct sequencing of the remaining regions of the gene. Data are presented on the yield of mutation carriers by category of family history and by stage of analysis.