Objective:To determine whether the protein expression of ribonucleotide reductase subunit 1(RRM1) and breast cancer susceptibility gene 1(BRCA1) in tumor tissue could predict the efficacy of gemcitabine combined with cisplatin (GP) on stage ⅢB/Ⅳsquaomas lung cancer. Methods:A total of 89 stage ⅢB/Ⅳsquaomas lung cancer patients were included,only 78 patients were evaluated. Bronchoscopy or lung puncture tumor biopsies samples were obtained and RRM1,BRCA1 protein expression were examined immunohistochemically before chemotherapy,then the patients were randomly assigned to received 4 cycles of GP chemotherapy regiments. Follow-up was done afterwards until the patient died or could not be informed. Response rate (RR),overall survival (OS) and time to tumor progression (TTP) were assessed. Results:Among 78 evaluated patients,the positive expression rates of RRM1 and BRCA1 were 47.4%(37/78) and 51.3%(40/78),respectively. There was no significant difference between positive expression rates and patients’ clinical characteristics. According to the different levels of RRM1 and BRCA1,the patients were divided into four groups:group A (low expression of both RRM1 and BRCA1),group B (high expression of both RRM1 and BRCA1),group C (high expression of only RRM1) and group D (high expression of only BRCA1). The RR was higher in group A than in other three groups (group A 59.1%,group B 38.1%,group C 42.1 %,group D 43.8%). The OS and TTP were longer in group A than in other three groups[OS:group A(617.4 ± 19.6)days,group B(299.2 ± 20.5)days,group C (336.6 ± 22.7)days,group D(324.7 ± 24.2)days;TTP:group A(274.9 ± 21.8)days,group B(138.8 ± 18.0)days, group C(172.5 ± 17.3)days, group D(167.6 ± 19.8)days]. There were no significant difference among group B,C,and D. Conclusion:The expression level of RRM1 and BRCA1 in sequomas lung cancer is probably predictive factor of the efficacy of GP chemotherapy regiments. It is more suitable for squaomas lung cancer patients who expressing lower RRM1 and BRCA1 to adopt GP chemotherapy regiments.