The aim of the present study was to investigate the expression of the transcription factor Ki-67, ER, PR,Her2/neu, p21, EGFR, and TOP II-α in the tumor tissue of patients with invasive ductal carcinoma(IDC); inaddition, we examined correlations between these markers. Two hundred and sixteen IDC patients, who werenot previously been treated with chemo- or radiotherapy, were included in the study. All tumors were grade I-III.Expression of molecular markers was determined by immunohistochemical analysis on paraffin-embedded tissuesections. Follow-up data were collected for 3 months to 10 years and analyzed for tumor recurrence, survival time,and prognostic risk factors. We determined Ki-67 expression correlates with the expression of ER, PR, HER-2,EGFR, and TOP-α, as well as lymph node involvement, high tumor grade, lymphovascular invasion, high tumorstage, and high TNM stage in IDC. Positive Ki-67 expression was a risk factor for rapid tumor recurrence andmay help tumor progression, leading to poor prognosis in IDC. Ki-67 was directly correlated with EGFR, TOPII-α, lymph node involvement, high tumor grade, lymphovascular invasion, high tumor stage, and high TNMstage in the hormone receptor subtypes of breast cancer. In triple negative breast cancer, Ki-67 correlated withTOP II-α. Expression of Ki-67 correlated with that of ER, PR, HER-2, EGFR, TOP II-α, and p21. In addition,the biomarker Ki-67 has a role as a prognostic factor and indicates a poor prognosis in IDC.