We applied microarray gene expression profiling to lungs from mouse strains having variable susceptibility to lung tumour development as a means to identify, within known quantitative trait loci (QTLs), candidate genes responsible for susceptibility or resistance to lung cancer. At least eight chromosomal regions of mice have been mapped and verified to be linked with lung tumour susceptibility or resistance. In this study, high density oligonucleotide arrays were used to measure the relative expression levels of >36 000 genes and ESTs in lung tissues of A/J, BALB/cJ, SM/J, C3H/HeJ, and C57BL/6J mice. A number of differentially expressed genes were found in each of the lung cancer susceptibility QTLs. Bioinformatic analysis of the differentially expressed genes located within QTLs produced 28 susceptibility candidates and 22 resistance candidates. These candidates may be extremely helpful in the ultimate identification of the precise genes responsible for lung tumour susceptibility or resistance in mice and, through follow up, humans. Complete data sets are available at http://thinker.med.ohio-state.edu.