Topoisomerase II-alpha (Topo II-alpha) is a nuclear enzyme. Its expression rises rapidly at the end of the S to G2/M phase and falls after the mitotic process ends. We have studied the immunohistochemical expression of Topo II-alpha in breast cancer and its correlation with the menopausal state, tumor type, size, lymph node metastases, stage, and estrogen and progesterone positivity. Histological sections from 50 breast cancers were immunohistochemically stained for Topo II-alpha. The percent of positive cells at the area of highest staining was recorded as Topo index. The correlation between the course of disease, survival and Topo II-alpha index was statistically significant, p<0.001. High-grade tumors showed higher Topo II-alpha levels, than those of intermediate and low-grade, p<0.01. A significant association was found between estrogen receptors positivity and Topo II-alpha, p<0.05. A higher Topo II-alpha index indicates higher probability for recurrence of the disease and overall survival. Therefore, Topo II-alpha expression has a prognostic value in breast carcinoma.