BACKGROUND: We previously showed the 2-year OS rate, the primary endpoint, of 90% in a phase II trial of gefitinib induction followed by chemoradiotherapy (CRT) in unresectable, stage III, EGFR-mutant, non-small-cell lung cancer (NSCLC). However, neither long-term survival data nor late-phase adverse event profiles have been presented. PATIENTS AND METHODS: Patients with unresectable, EGFR-mutant, stage III NSCLC were administered gefitinib monotherapy for 8 weeks. After confirming no disease progression during induction therapy, cisplatin and docetaxel on days 1, 8, 29, and 36 with concurrent radiotherapy at a total dose of 60 Gy were subsequently administered. RESULTS: In the enrolled twenty patients, the 5-year OS rate and median survival time were 70.0% [95% confidence interval: 45.1-85.3] and 5.5 years [4.91-NE], respectively, whereas 5-year PFS rate and median PFS time were 15.0% (3.7-33.5) and 1.4 years [0.69-2.29], respectively. Efficacy did not seem influenced even if radiation field was re-planed in response to the effect of gefitinib induction. As for late adverse events, pulmonary fibrosis occurred in 7 patients (35%). The median time from completion of CRT to the occurrence of the event was 245 days. All were grade 1, and there was no evidence of cavitation of the lesions or chronic infections such as Aspergillus infection during the course of the disease. One case of small cell lung cancer occurred during the period. CONCLUSIONS: With longer follow-up time, we demonstrated favorable efficacy with tolerable toxicity profiles in the EGFR-TKI induction followed by standard CRT in EGFR-mutant, stage III, NSCLC. TRIAL REGISTRATION NUMBERS: UMIN00005086. https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr.cgi?function=brows&action=brows&recptno=R000006047&type=summary&language=EjRCTs071180036 . https://jrct.niph.go.jp/latest-detail/jRCTs071180036.