Abstract: Objective 　To study the correlation between the expression of AP-2 transcription factor and overexpression of c-erbB-2 in breast cancer. Methods 　The expression of AP-2 and c-erbB-2 in 128 cases of breast cancer tissue was evaluated by immunohistochemical staining using st reotavidin peroxidase (SP) technique. Results 　The positive rates for AP-2 and c-erbB-2 in breast cancer were 34. 38 % and 30. 46 %.The expression of AP-2 did not correlate with ages of the patient s (χ= 2. 3, P<0. 05) 、size of tumor (χ= 2. 58, P<0. 05) and lymphatic metastasis (χ= 0. 32, P<0. 05) . The expression of AP-2 (χ= 7. 46, P <0. 05) and c-erbB-2 (χ= 6. 80, P<0. 05) were positively correlated with the histological grade of breast cancer . A significant correlation was found between the expression of AP-2 and c-erbB-2 ( r =0. 87, P<0. 01) . There was an positive relationship between AP-2 and c-erbB-2 (0; 1) . Conclusion 　 There was overexpression of AP-2 transcription factor in breast cancer, and AP-2 such as c-erbB-2 may serve as another index for indicating prognosis and choosing medicine of chemical treatment .