The invasive mammary cancer is the most frequent malignant tumor of women. Different inherited or acquired molecular genetic alterations have been identified in human breast cancers. A fraction of these cancers, as part of their development, undergoes gene amplification. Among the potential prognostic factors are included the biomarkers which measure or are associated with biological processes involved in tumor progression. Evaluation of HER-2 status is important in the management of patients with breast carcinoma, especially for the identification of those who are eligible for immunotherapy. The aim of our study was to evaluate HER-2 amplification status of human breast cancers by FISH and immunohistochemistry. From the total of 50 tumors included in the study, 17 (34%) presented different degrees of positivity; 33 (66%) did not express the oncoprotein HER-2. HER-2 gene and chromosome 17 status were tested in HER-2 2+ cases using FISH technique. FISH analysis may be useful to better evaluate HER-2 status in breast cancer in uncertain cases, where the immunohistochemistry score is 2+. HER-2 testing results have an important role in the clinical management of breast cancer patients. The identification of HER-2 positive tumors is certainly crucial in order to identify patient candidates for anti-HER-2 therapies.