Background Checkpoint kinase 2(CHK2)is a DNA damage-activated protein kinase which is involved in cell cyclecheckpoint control.CHK2 gene could be a candidate gene for colorectal cancer susceptibility.But there are fewsystematic reports on mutation of CHK2 in colorectal cancer.Methods The mutations of all 14 exons of CHK2 in 56 colorectal cancer cell lines were screened systematically,usingdenaturing high-performance liquid chromatography(DHPLC)to screen the mismatches of the CHK2 exons amplifiedproducts,and then the suspected mutant cell lines were scanned by nucleotide sequence analysis.Results VACO400 in CHK2 exon la was suspected to have mutation by DHPLC and confirmed by sequence,but thiswas nonsense mutation.C106,CX-1,HT-29,SK01,SW480,SW620 and VACO400 in CHK2 exon 1b were confirmed tohave the same nonsense mutation in 11609 A>G.DLD-1 and HCT-15 in CHK2 exon 2 were confirmed to have missensemutation R145W,which was heterozygous C>T missense mutation at nucleotide 433,leading to an Arg>Trp substitutionwithin the FHA domain.Conclusions The CHK2 mutation in colorectal cancer is a low frequency event.There are just 10 cell lines to havesequence variations in all the 14 exons in 56 colorectal cancer cell lines and only DLD-1/HCT-15 had heterozygousmissense mutation.These findings may give useful information of susceptibility of colorectal cancer as single nucleotidepolymorphysim. Background Checkpoint kinase 2 (CHK2) is a DNA damage-activated protein kinase which is involved in cell cyclecheckpoint control. CHK2 gene could be a candidate gene for colorectal cancer susceptibility. But there are fewsystematic reports on mutation of CHK2 in colorectal cancer. Methods The mutations of all 14 exons of CHK2 in 56 colorectal cancer cell lines were screened systematically, using degeneration high-performance liquid chromatography (DHPLC) to screen the mismatches of the CHK2 exons amplified products, and then the suspected mutant cell lines were scanned by nucleotide sequence analysis. Results VACO400 in CHK2 exon la was suspected to have mutation by DHPLC and confirmed by sequence, but thiswas nonsense mutation. C106, CX-1, HT-29, SK01, SW480, SW620 and VACO400 in CHK2 exon 1b were confirmed to the same nonsense mutation in 11609 A> G.DLD-1 and HCT-15 in CHK2 exon 2 were confirmed to have missensemutation R145W, which was heterozygous C> T missense mutation at nucleotide 433, leading to an Arg> Trp substitution with in the FHA domain. Conclusions The CHK2 mutation in colorectal cancer is a low frequency event. Here are just 10 cell lines to have sequence mutations in all the 14 exons in 56 colorectal cancer cell lines and only DLD-1 / HCT-15 had heterozygousmissense mutation.These findings may give useful information of susceptibility of colorectal cancer as single nucleotide polymorphismsysim.