: Breast cancer has the highest incidence among all female patients with different cancer types. It is a lethal disease which threaten women's health. There are many prognostic and predictive factors that implicated in breast cancer. The expression of Ki-67 is strongly associated with cancer proliferation and is a known indicator of breast cancer prognosis and outcome. Ki-67 expression levels are also useful to inform treatment decision making in some cases. As a result, measurement of Ki-67 is routinely done during pathological tumor evaluation.