Abstract: Abstract:Objective To detect the expression of human epidermal growth factor receptor-2（HER-2）gene in breast cancer tissues and metastasis lymph node and to compare the results from fluorescence in situ hybridization (FISH) and with that from immunohistochemistry assay (IHC). Methods The expression of HER-2 gene were measured by FISH and IHC methods in 187 cases of breast cancer tissues and 76 cases of metastasis lymph nodes. The results from the two methods were compared and analyzed with clinicopathological data. Results In breast cancer tissues, 43 cases present positive and 144 cases present negative for HER-2 gene measured by FISH assay. Twenty-two cases showed +++, 40 cases showed ++ and 125 cases showed 0/+ for HER-2 measured by IHC. FISH-positive rate in IHC +++ was 90.9% (20/22), in IHC ++ was 52.5% (21/40) and in IHC -/+ was 1.6% (2/125),respectively. There are significant differences between IHC and FISH (P<0.001). HER-2 expression was significantly correlated with lymph node metastasis (P<0.05). The discrepancy of HER-2 expression were 11.8% (9/76) between breast cancer primary tumors and paired lymph node metastasis Conclusion Detecting HER-2 expression by FISH is more accuracy than by IHC, especially for IHC ++ patients. The expression of HER-2 is discrepancy between primary breast cancer and metastastic lymph nodes.