Now molecular epidemiology was meaningful. On the surface of the tumor, cells will express its antigen specific as a tumor cell (example: TSA, tumor specific antigen) and can induce cellular immune response. The result of interactions between group antigens with the immune system cells of the body will cause a rise in the expression of lymphocytes CD8+. The aim of this research is to find out differences in the number of lymphocytes CD8+ expression between benign and malignant tissues. This research is a laboratory experiment with the approach of cross sectional. Samples are taken from benign and malignant tissue biopsy of the breast and cervical uterine that were got from anatomical pathology laboratory, period January to February 2004. A technique using random sampling, is sample acquiring 30 benign cancer and 30 malignant of the breast or cervical uterine. To find out the significance of the difference in the number of lymphocytes CD8+ between benign and malignant of breast or cervical uterine, we used a statistical analysis Anova in SPSS for Windows 15.0 program. In this research the number of lymphocytes average in the benign cancer is 2.9667 cells (breast) and 4.2667 cells (cervical uterine), on the other side malignant tissue of 23.8000 cells (breast) and 25.0333 cells (cervical uterine). From the statistical analyses with Anova the number of lymphocytes CD8+ was very significant differences between benign and malignant of the breast or cervical uterine tissue (p < 0.001). The conclusion of this research is that there is a significant increase of the number of lymphocytes CD8+ expression in cancer tissue.