Objective: To study the relationship between clinical pathologic characteristics, treatment modalities and prognostic factors in HER-2 (Human Epidermal growth factor Receptor-2) overexpressed breast carcinoma. Materials and Methods: Major clinico-pathological factors including therapeutic modalities and survival status of 371 breast cancer patients with HER2 over-expression, teated at Yantai Yuhuangding Hospital from March of 2002 to December of 2010 were retrospectively studied, with special attention focused on survival-related factors. Results: The median age of the total 371 patients in this study was 48 years at time of diagnosis, among which, the leading pathological type was infiltrating ductal carcinoma (92.5%); 62.8% presented with a primary tomor larger than 2 cm in diameter at diagnosis, 51.0% had axillary lymph node (ALN) metastases; ER (Estrogen receptor)/PR (Progesterone receptor) double negative occured in 52.8% of cases, and PCNA (proliferation cell nuclear antigen) (+++) was found in 55.1%. HER-2 overexpressed patients were usually in advanced stage when the diagnosis was made (72.8% at stages IIA~IIIC). The prognosis and survival were assessed in 259 patients with complete follow-up data. 5-year DFS (disease-free survival) and OS (overall survival) rate was 68.0% and 78.0% respectively. Univariate analysis revealed that age, tumor size, ALN metastases, LVSI (lymph-vascular space involvement), PCNA status, hormonal therapy, chemotherapy cycles, and HER-2 overexpression, correlated closely with the prognosis. ALN metastases, LVSI, PCNA status and chemotherapy cycles were independent predictors of survival. Conclusions: HER-2 overexpressed breast cancer has special clinical and pathological characteristics, with advanced clinical stages and high rate of ER/PR double negative. Lymph node metastases, LVSI, PCNA and chemotherapy cycles are independent predictors of prognosis.