Objective To elucidate the association between the polymorphism of STKl5 and the risk of Non-Small Cell Lung Carcinoma. Methods In a case-control study,genotypes of STKl5 Phe31Ile were determined by PCR-RLFP in 275 patients with Non-Small Cell Lung Carcinoma and 500 controls. Their association with Non-Small Cell Lung Carcinoma risk and pathological outcome were analyzed. The adjusted odds ratios (ORs) and 95%confidence intervals (CIs) were calculated using logistic regression model. Results The frequency of the three genotypes (Phe/Phe, Phe/Ile, Ile/Ile) of STKl5 Phe31 Ile in Non-Small Cell Lung Carcinoma patients was 21.4%, 24.6% and 54.0% respectively, which was significantly different from that in the controls (25.6%, 39.7% and 34.7%) (P=0.024).Subjects with the Ile/Ile genotype had an increased risk for the occurrence of Non-Small Cell Lung Carcinoma compared with those with the Phe/Phe genotype (OR=5.429, 95%CI=1.478~24.542). The risk was more significant in the subjects who smoked (OR=5.429, 95%CI=1.478~24.542). No significant association was observed between the STKl5 polymorphism and Non-Small Cell Lung Carcinoma pathological outcome. Conclu-sion Our study suggestes that STKl 5 Phe31 Ile polymorphisms are likely to be associated with an increased risk of Non-Small Cell Lung Carcinoma in Chinese people.