Objective: To investigate the mechanism of resistance to docetaxel in human lung cancer.Methods: Human lung carcinoma SPC-A1/Docetaxel cells were derived from parental SPC-A1 cells by continuous exposure to increasing concentration of docetaxel. The drug sensitivity was measured by MTT assay in vitro. The cDNA microarray identified a set of differentially expressed genes, and some genes were confirmed by RT-PCR. P-glycoprotein level was measured by flow cytometry analysis.Results: The results of drug sensitivity measured by MTT assay showed that SPC-A1/Docetaxel cells were 13.2-fold resistant to docetaxel and cross-resistant at varying levels to other drugs. The cDNA microarray results identified a set of differentially expressed genes, which showed 428 genes that were up-regulated and 506 genes that were down-regulated in SPC-A1/Docetaxel cells, and some genes were confirmed by RT-PCR. Flow cytometry analysis suggests expression of P-glycoprotein (P-gp) was more abundant in SPC-A1/Docetaxel cells than in the parental cells and docetaxel selection reduces the apoptotic response.Conclusion: The results suggest that docetaxel selection led to changes in gene expression that contribute to the multidrug resistance phenotype.