Objective To explore the clinical significance of KRAS mutation detection in colorectal adenocarcinoma.Methods Paraffin-embedded tissue specimens were obtained from 440 patients with colorectal adenocarcinoma.The genomic DNA was extracted.Mutations of exon 2 of KRAS gene were examined by PCR and direct seqaencing.Results Somatic mutations of KRAS gene were identified in 146 cases,with the mutation rate of 33.2％ (146/440).Among these 146 patients,KRAS mutation involved codon 12 in 118 patients,including 35G ＞ A (Gly12Asp,62 cases),35G ＞ T (Gly12Val,35 cases),34G ＞ T (Gly12Cys,9 cases),34G ＞ A (Gly12Ser,6 cases),35G ＞ C (Gly12Ala,5 cases),and 34G＞ C (Gly12Arg,1 case); in 27 patients the mutation involved codon 13,including 38G ＞ A (Gly13Asp,25 cases),38G ＞ C (Gly13 Val,1 case) and 37G ＞ T (Gly13 Cys,1 case) ; and in one patient,the mutation involved codon 14 with 40G ＞ A (Val14Ile).The status of KRAS or codon 12 mutations in colorectal adenocarcinoma was related to patients' gender (P =0.021 and P =0.030,respectively),and this significant correlation to females was conserved in clinical stage Ⅲ (P =0.007 and P =0.003,respectively),but not in stages Ⅰ,Ⅱ,and Ⅳ.The statns of KRAS or codon 12 mutations was also related to tumor stage.Between stage Ⅱ and stage Ⅳ,the mutation rate of KRAS and codon 12 showed significant difference (P =0.028 and 0.034,respectively).Between stage Ⅲ and stage Ⅳ,only the codon 12 mutation rate showed significant difference (P =O.011).Codon 13 mutation was not related to tumor stage.Conclusion About one third of patients with colorectal adenocarcinoma have KRAS gene mutation,which might be related to patients' gender; and could be consistently detected by PCR and direct sequencing.