Germ-line mutations in BRCA1 gene contribute to a majority of familial breast and ovarian cancers. A group of 23 Tamil Nadu (south India) patients with positive family history for breast and ovarian cancer were screened for BRCA1 mutations by conformation sensitive gel electrophoresis (CSGE) followed by sequencing. In the present study, we report a novel 1307delT mutation in exon 11 of BRCA1 gene in a 43-year-old woman of Indian origin with breast cancer. This mutation gives rise to a premature stop codon at amino acid residue 409 and also creates a novel DdeI restriction site. The same mutation was also detected in the patient's maternal uncle and his son through extended family analysis. The 1307delT is a novel mutation that has not been documented in any population or published report to the best of our knowledge. Identification of this novel mutation stresses the need for developing a database of BRCA1 mutations, which will aid in breast cancer screening in this population.