Breast cancer is the most common malignancy in women. Humanepidermal growth factor receptor (HER-2/neu) is an important prognosticindicator in breast cancer. This study was performed on 49 breast cancerpatients, 16 benign breast lesions and 15 age matched normal controls.Serum HER-2/neu was measured by Immunochemiluminescence tocorrelate with its status by Immunohistochemistry (IHC), pathologicalgrade, estrogen and progesterone receptor status of tumors. Serum HER-2/neu was significantly increased in patients who had +ve IHC whencompared to those who were –ve. Serum HER-2/neu should complementIHC, but whether or not it can substitute it, is still a subject of study.