Summary Background Exon 19 deletion and L858R point mutation in exon 21 of the epidermal growth factor receptor ( EGFR ) are the most commonly encountered mutations in patients with non-small cell lung cancer (NSCLC) and predict better clinical outcomes following treatment with EGFR-tyrosine kinase inhibitors (TKIs). The inflammatory indicator neutrophil-to-lymphocyte ratio (NLR) in peripheral blood serves as a predictive factor for NSCLC patients treated with chemotherapy. Here, we aimed to evaluate the correlation between NLR and clinical efficacy of EGFR-TKIs in NSCLC patients harboring EGFR mutations. Methods We retrospectively collected information of 205 patients with advanced NSCLC harboring exon 19 deletion or L858R point mutation and receiving gefitinib or erlotinib. The clinical outcomes in the NSCLC patients were evaluated based on NLR level before EGFR-TKI therapy. Results The optimal cut-off value for NLR was 3.55. The response rates in the low-NLR and high-NLR groups were 69.2% and 51.5%, respectively. The median progression-free survival (PFS) in the low-NLR and high-NLR groups were 15.7 months and 6.7 months, respectively. The median overall survival (OS) in the low-NLR and high-NLR groups were 37.6 months and 19.2 months, respectively. The multivariate analysis identified performance status (PS), NLR, stage, and smoking status as independent predictors of PFS. Moreover, the PS and NLR were identified as independent predictors of OS. Conclusions NLR was a significant predictor of clinical efficacy and OS in NSCLC patients harboring EGFR mutations treated with gefitinib or erlotinib.