Objective:To find potential molecular targets for breast cancer diagnostics by analyzing and comparing the proteomes expressed in human breast carcinoma,paracancerous tissues and normal tissues. Methods:The proteins expressed in these tissues were analyzed by the two-dimensional gel electrophoresis. The differentially expressed proteins in tumors were also analyzed by mass spectrometry(MS). Results:Protein extracts of individual sample in each type of tissues were separated on two-dimensional gels. There were twenty differentially expressed proteins in the tissues of breast cancer. Thirteen proteins were successfully identified by MS,in which eight proteins were overexpressed in tumors and the other five proteins were underexpressed. Conclusion:Significant discrepancies in protein expression exist among breast cancer tissues,paracancerous tissues and normal tissues. Some of the differentially expressed proteins found by the proteomic approach may be potential molecular targets for breast cancer diagnosis.