Abstract: Objective To explore the clinical value of immunohistochemistry (IHC) in screening the epidermal growth factor receptor(EGFR) mutation in lung cancer patients. Methods The two mutationspecific antibodies targeting the delE746-A750 mutation in exon 19 and L858R mutation in exon 21 were used for IHC, and the method of direct DNA sequencing was served as control. Results In this investigation, we found 3(6.25%) cases scored 0, 11(20.75%) scored 1, 22(81.48%) scored 2, 8(100%) scored 3 assessed by IHC existed EGFR mutation in direct DNA sequencing analysis. When score≤1+ was considered to be negative and score≥2+ to be positive, the agreement between the two different detection methods was highest(κ=0.683), which the sensitivity was 71.43% and specificity was 94.68%. In the same time, the positive predictive value (PPV) was 85.71% and the negative predictive value (NPV) was 88.12%. Conclusion The score of EGFR mutation assessed by IHC≤1 is considered to be negative mutation whereas score≥2 to be positive mutation.