For epidermal growth factor receptor (EGFR)-mutated non-small cell lung cancer (NSCLC), administration of EGFR tyrosine kinase inhibitors (TKIs) is mandatory to prolong survival. To date, a comparison of second- and third-generation EGFR-TKIs has not been reported as far as we are aware. We retrospectively investigated the survival time of patients diagnosed with EGFR-mutated advanced or recurrent NSCLC who had received afatinib, a second-generation EGFR-TKI, or osimertinib, a third-generation EGFR-TKI, as the first-line treatment. Among the 49 patients included in the study, 15 received afatinib and 34 received osimertinib. No significant differences in overall survival were observed between the two groups [afatinib vs. osimertinib=36 vs. 33 months (hazard ratio=2.917, 95% confidence interval=0.780-10.905; p=0.112)]. T790M mutation was detected in three of the patients in the afatinib group, and all three subsequently received osimertinib. The median overall survival of these three patients and of the 12 without the mutation were 63 and 36 months, respectively. There was no apparent difference in the effect on survival between second- and third-generation EGFR-TKIs, whereas the sequential administration of second- followed by third-generation EGFR-TKIs appeared to confer a better long-term prognosis. Copyright © 2021 International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.