Abstract: Objective To explore the correlation between the expression of RASSF1A and Elf-1 proteins and clinicopathological fea-tures of non-small cell lung cancer（NSCLC）. Methods A tissue chip array containing 72 NSCLC tissue samples and 10 normal lung tissue samples was constructed，and immunohistochemistry（PV9000）was used to measure the expression of RASSF1A and Elf-1 pro-teins. Results Both RASSF1A and Elf-1 were heterogeneously expressed in NSCLC tissue. RASSF1A protein was expressed in 34/72 （47.22%） of NSCLC tissues，a significantly lower proportion than the 10/10（100%） of normal lung tissues expressing RASSF1A.In addition，RASSF1A protein levels differed significantly between NSCLC tissue and normal lung tissue（P=0.002）.For example， RASSF1A protein levels were significantly higher in cases with lymph node metastasis than in cases without it（X²=4.379，P=0.036）. Significant differences were also observed between groups at different clinical stages（X²=17.979，P=0.000）.Elf-1 protein was detected in 53/72（73.61%） of NSCLC tissues but in only 2/10（20%） of normal lung tissues.Elf-1 protein levels differed significantly between the two types of tissue（P=0.001）.Expression of Elf-1 was related to tumor differentiation（X²=7.116，P=0.028），lymph node metastasis （X²=5.304， P=0.021） and clinical staging（X²=6.791， P=0.034）.Levels of RASSF1A and Elf-1 proteins correlated negatively with each other in NSCLC tissue（r =-0.433，P =0.000）. Conclusions The down-regulation of RASSF1A and up regulation of Elf-1 may be asso-ciated with the occurrence，progression and prognosis of NSCLC.The relative expression of RASSF1A and Elf-1 may play an impor-tant role in early diagnosis of NSCLC，and serve as a molecular indicator for predicting invasion and metastasis.