The bcl-2 proto-oncogene was first described as a result of the chromosomal translocation t(14:18) seen in a large number of follicular B-cell lines. Bcl-2 is so far unique a proto-oncogene in that it codes for an inner mitochondrial membrane protein. This protein regulates the programmed cell death called apoptosis. This study was designed to investigate expression of bcl-2 protein in 81 human breast cancer by using immunohistochemical staining with the monoclonal antibody of bcl-2 protein. Also this factor was compared with established clinicopathological prognostic factors and hormone receptors. The bcl-2 protein expression was positive in 38(47%) cases and was negative in 43(53%) cases. There was significant correlation between bcl-2 protein expression and histologic grade(p=0.014). Positive expression of bcl-2 protein was correlated with positive estrogen(p=0.051) and progesterone(p=0.059) receptors, but this correlation was not significant. Bcl-2 expression failed to show its prognostic role for overall(p=0.115) and disease free(p=0.214) survival. In conclusion, the bcl-2 protein is often expressed in half of breast cancer, and its expression is associated with histologic grade and hormone receptor status, but the overall and disease free survival of breast cancer patient do not appear to be influenced by bcl-2 protein expression.