Tehran University of Medical Sciences Acta Medica Iranica 0044-6025 34 3-4 1996 12 15 80 82 P. Mehdipour M. Atri 2015 09 28 Breast cancer is preservative of the genetic heterogeneous alterations. In the present investigation, fluorescence in situ hybridization (FISH) was performed on the fresh primary tumours of 6 patients with infilterating ductal carcinoma. DNA-probe for centromere of chromosome 3 (3cen) was applied and in the total analysis, the majority of interphases presented 1 signal (33.6%) which followed by 3 (28,8%), 2 (16.8%) and 4 (13.5%) signals. Only two tomours showed the +presence of more than 6 signals. The presence of 2 signals could be observed in only one tumour (19.6%). In two tumours, 3 signals (33.1%) was considered as the most frequent alteration and followed by more than 6 signals (25.5% and 18.3% respectively), in tumour ID 27, and 3 signals (43.1%) followed by 1 and 4 signals (30.1% and 17.2% respectively) in tumour ID 33. It is concluded that the FISH-technique is able to clarify and diagnose the numerical alterations of chromosome 3 cen in tumour cells of BC patients. https://acta.tums.ac.ir/index.php/acta/article/view/1699 https://acta.tums.ac.ir/index.php/acta/article/download/1699/1692