This retrospective study reviewed the medical records of EGFR exon19 mutant advanced NSCLC patients undergoing EGFR-TKIs treatment, so as to evaluate the association of different subtypes of exon19 mutation with EGFR-TKI efficacy in EGFR-mutant advanced non-small cell lung adenocarcinoma patients. The gene discussed is EGFR; the disease is non-small cell lung adenocarcinoma.