We found that the serum HER2 level measured by dotblot assay was significantly correlated with tissue HER2 status in breast cancerpatients (P = 0.001), and alsosignificantly correlated with HER2 level measured by ELISA(P = 1.06×10−11).Compared with ELISA method, the specificity and sensitivity of dot blot assaywere 95.3% and 65.0%, respectively. Here, ERBB2 is linked to medical procedure.