Objective To evaluate cell proliferating activity and expression of P53. c-erbB-2 oncogene protein in breast carcinoma and premalignant lesions in breast and to investigate the relationship of proliferating cell nuclear Aantigen (PCNA) with p53. c-erbB-2 oncogene protein. Methods Immunohistoch emical reaction of PCNA and p53. c-erbB-2 oncogene protein was evaluated in 61 benign lesion and 25 malignant breast paraffinembeded specimens. The relationships of PCNA-Labeling Index (PCNA-LI) and p53 、c-erbB-2 oncogene protein with hyperplasia condition and PCNA-LI with p53、c-erbB-2 oncogene protein were analyzed. Results The expression of PCNA and p53. c-erbB-2 oncogene protein significantly increased with the increased breast atypical hyperplasia condition. PCNA-LI of positive expression for p53 or c-erbB-2 was significantly higher than that of negative respectively (t =2.9040

P <0.01

t =3.2333

P<0. 01). Conclusion The expression of PCNA and p53. c-erbB-2 oncogene protein may indicate the risk of breast premalignant for carcinoma and direct clinical treatment and follow-up for premalignant

and in the meantime the cell proliferating activity had close relation to p53. c-erbB-2 oncogene activation and protein accumulation.