Platinum-based chemotherapy with third generation drugs (such as gemcitabine) is an efficacious regimen of first-line treatment of patients with advanced, unresectable non-small cell lung cancer (NSCLC), without activating EGFR mutations. Mechanism of action of cytostatics are distortions in the DNA. ERCC1 and RRM1 are key proteins involved in the repair of DNA, thus, they may be responsible for the ineffectiveness of therapy. We investigated whether ERCC1 (19007C>T) and RRM1 (-37C>A) polymorphisms impact response to chemotherapy and survival in 62 patients with NSCLC treated with platinum and gemcitabine. Single nucleotide polymorphisms (SNPs) were assessed using a PCR-RFLP method in DNA isolated from PBLs. There were no statistically significant relationships between ERCC1 genotypes and response to therapy (p=0.581, χ2=1.09) as well as patient overall survival (OS). Carriers of the RRM1 AC genotype showed disease progression significantly more frequently (p=0.019, χ2=5.473) compared to carriers of the AA or CC genotypes. Carriers of the ERCC1/RRM1TT/CC genotype combination showed disease control significantly more frequently (p=0.047, χ2=3.95) compared to carriers of other genotype combinations. Patients with AA or CC genotypes of RRM1 showed significantly higher progression-free survival probability (p=0.0001, HR=0.39, 95% CI, 0.22-0.70) and OS probability (p=0.0104, HR=0.39, 95% CI, 0.18-0.82) compared to those with the AC genotype. In Cox regression model, poor performance status (p=0.0016, HR=4.78, 95% CI, 1.82-12.56), AC genotype of RRM1 gene (p=0.0414, HR=2.47, 95% CI, 1.04-5.87), lack of prior surgical treatment (p=0.0425, HR=4.71, 95% CI, 1.06-20.92) and lack of subsequent lines of treatment (p=0.0127, HR=3.23, 95% CI, 1.29-8.11) were significantly associated with shortening of patient survival. The analysis of RRM1 (-37C>A) more than ERCC1 (19007C>T) polymorphism may be a promising tool in the qualification of NSCLC patients for chemotherapy containing platinum compounds and gemcitabine.