DNA expression profiling using microarray technology has been applied to studies on the molecular classification of lung cancers, pathogenetic alterations in gene expressions and cellular path-ways, prediction of prognosis and metastasis, customized therapies, and drug development. Due to the wide variation in technical factors, different cohorts of patients and biological heterogeneity, the major hur-dle to successful clinical application is lack of robustness, reliability and reproducibility of data. With better standardization and better analytic approaches to cut down the noises from the high dimensionality of data, microarray technologies may be ready to make its way to the doctor's office with contribution to personal-ized treatment of lung cancer in the future.