This is a prospective study including seventy-five Egyptian female breast cancer patients attending the kasr El-Aini Center of Radiation Oncology and Nuclear Medicine (NEMROCK) during the period (1999-2001). Sixty patients with non-metastatic and fifteen patients with metastatic breast cancer. Elevated serum level of HER2 by serum EIA was found in 26.7% of non-metastatic patients and in 40% of metastatic patients. HER2 positive status correlated significantly with negative progesterone receptor and negative estrogen receptor. Lobular carcinoma, medullary and papillary subtypes were all negative. Regarding non-metastatic patients and after two-year of follow-up, relapse was seen in 15% of patients. Axillary lymph node involvement and tumor size were the most significant prognostic factors for relapse. There was no significant evidence of a relationship between serum HER2 positivity and disease-free survival in this study. However, Serum HER2 positivity had a significant prognostic factor in metastatic breast cancer regarding two-year survival (50.2% vs 77.78%, p value = 0.04).