Background: Afatinib, an epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI), has now become standard targeted therapy for EGFR-mutated lung adenocarcinoma patients in Indonesia, and approved under universal health coverage scheme in Indonesia. Objectives: This study aimed to evaluate the outcomes and efficacy of afatinib therapy in lung adenocarcinoma patients with EGFR mutations at Persahabatan General Hospital, a tertiary referral respiratory hospital, under universal health coverage scheme. Methods: This retrospective cohort study was conducted based on medical records of EGFR-mutated lung adenocarcinoma patients who received afatinib at Thoracic Oncology Outpatient Clinic Persahabatan Hospital, between January 2018 and December 2021. All patients initially received afatinib at a dose of 40 mg dose, with some had dose reduction to 20 or 30 mg. Survival analysis was conducted using Kaplan-Meier and Log-Rank Test. Results: Among 86 participants, 78% were diagnosed with stage IVA disease at the initiation of afatinib therapy. Exon 19 deletion were observed in over 50% of patients, and pleural metastases were present in nearly 60%. The median progression-free survival (PFS) was 13 months (95% CI: 10.5-15.5), and the median overall survival (OS) was 17 months (95% CI: 14.9-19.1). The one-year survival rate was 65.1%. Dose reduction occurred in 43% of participants, with no significant differences in survival outcomes. Median PFS was 15 months (95% CI: 12.4-17.6) with dose reduction and 12 months (95% CI: 8.1-15.9) without (P = 0.85). Median OS was 17 months (95% CI: 14.9-19.1) with dose reduction and 19 months (95% CI: 13.7-24.3) without (P = 0.59). Conclusions: Afatinib has comparable efficacy for EGFR-mutated lung adenocarcinoma patients and dose adjustment did not affect the survival rate, in patient under universal health coverage program in Indonesia. © 2025, Angasreni et al.