Health-related quality of life (HRQoL) data complement conventional clinical endpoints when comparing adjuvant gefitinib with chemotherapy in patients with early-stage non-small-cell lung cancer (NSCLC) and epidermal growth factor receptor (EGFR) mutations. This study aimed to assess changes in HRQoL with adjuvant gefitinib vs chemotherapy in this patient group. In the phase III ADJUVANT trial, patients with completely resected, stage II-IIIA (N1-N2), EGFR-mutant NSCLC were randomized (1:1) to receive either gefitinib for 24 months or vinorelbine plus cisplatin (VP) every 3 weeks for four cycles. HRQoL was assessed as a secondary endpoint using the Functional Assessment of Cancer Therapy-Lung Cancer (FACT-L), Lung Cancer Symptom Scale (LCSS) questionnaires, and Trial Outcome Index (TOI) composite score. HRQoL dynamics, improvements, and time to deterioration were compared between groups. At baseline, 104 of 106, and 80 of 87 patients receiving gefitinib and VP, respectively, completed two questionnaires (FACT-L and LCSS). Baseline scores were balanced between groups. Although HRQoL fluctuated and gradually improved in both groups, longitudinally higher scores were reported with gefitinib than VP (FACT-L, odds ratio 418.16, 95 % confidence interval [CI] 2.75-63509.05, p =  0.019; LCSS, 1.13, 1.04-1.22, p =  0.003; TOI, 88.39, 4.40-1775.05, p =  0.003). Time to deterioration in HRQoL was delayed with gefitinib compared with VP (FACT-L, median 69 vs 6 weeks, hazard ratio 0.62, 95 % CI 0.42-0.90, p =  0.013; LCSS, median 45 vs 6 weeks, 0.63, 0.43-0.93, p =  0.020; TOI, median 164 vs 9 weeks, 0.51, 0.33-0.77, p =  0.001). Adjuvant gefitinib is associated with improved HRQoL over VP, supporting its use in patients with stage II-IIIA (N1-N2), EGFR-mutant NSCLC. Copyright © 2020. Published by Elsevier B.V.