Background: Class IV alcohol dehydrogenase (ADH7) acts as a multifunctional enzyme in the detoxifi cation of endogenousaldehyde, biosynthesis of retinoids, and metabolism of bioactive eicosanoid. The aim of this study was to assessADH7 expression and cellular localization in non-small cell lung cancer (NSCLC), including squamous cell carcinoma(SCC), adenocarcinoma (ADC) and large cell carcinoma (LCC). Materials and Methods: We used purifi ed class-specifi cantibody for ADH7 to elucidate the cellular distribution in a human NSCLC tissue microarray. An overall score was obtainedfor each sample based upon multiplying the staining intensity (0-3) and the extensiveness (0-100%). Mean±S.E.M.for each experimental group was calculated and compared. Results: Our results indicated a signifi cantly higher levelof expression of ADH7 in SCC (116.7±13.7) than ADC (26.5±4.8), LCC (37.5±12.5) and normal lung tissues (11.4±3.7) (all p < 0.005). No statistically signifi cant difference was observed between ADC, LCC, and normal lung tissues.ADH7 was mainly distributed in the epithelium of bronchiole, one of the origins of SCC. The tumor invasive front demonstrateda higher expression of ADH7, both in primary and metastatic SCC. Conclusion: Abundant expression of ADH7in SCC but not ADC and LCC makes it a potential biomarker for diagnosis of lung SCC.