Background: A T263P mutation is one of the rare EGFR mutation, located in 7p11.2, a change in the amino acid residue at position 263 in the epidermal growth factor receptor protein where L-threonine has been replaced by L-proline. This missense mutation in the EGFR extracellular (EC) domain is poor-known about EGFR EC domain mutations in lung cancer. Purpose: In this study, we firstly reported a patient with advanced lung adenocarcinoma haboring a rare EGFR mutations of T263P alone who benefited from first-line treatment with afatinib in Vietnam. Results: This patient achieved a partial response and had a progression-free survival of 5 months. After disease progression, this patient was subsequently administered several chemotherapy regimens and had an overall survival of 17 months. Conclusion: NSCLCs with rare T263P mutation reveal the response to afatinib, however prognosis is often poor.