In advanced non-small cell lung cancer (NSCLC), epidermal growth factor receptor (EGFR) mutations are one of the most frequent oncogenic drivers. They confer a favorable prognosis and strongly predict sensitivity to EGFR tyrosine kinase inhibitors (TKIs). Over the last decades, several EGFR genetic alterations, common and uncommon mutations, have been described in exons 18−21. Common mutations are exon 19 deletions (most frequently E746-A750) and exon 21 L858R substitution. Uncommon mutations include exon 18 G719X, exon 20 S768l, exon 21 L861Q and many other rare ones. This report describes the case of a 55-year-old woman with a newly diagnosed metastatic lung adenocarcinoma harboring two rare EGFR mutations and showing sustained response to osimertinib.