PURPOSE: Epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) are the preferred first-line option for patients with advanced, EGFR-mutant non-small cell lung cancer (NSCLC). Afatinib, a second-generation irreversible EGFR-TKI, has been extensively used in Greece in this setting; however, real-world data regarding molecular epidemiology and financial implications of afatinib use are lacking. MATERIALS AND METHODS: This was an observational, non-interventional, multicenter, retrospective cohort study, based on real-world data collected from the medical charts/records of patients treated with afatinib between 15/03/2015 and 25/06/2020 and were recorded on a web-based data capture system. Cox models were used to assess the prognostic significance of clinicopathological parameters with respect to clinical outcomes of interest. Cost analysis was conducted from a public third-payer perspective, and only direct medical costs reimbursed by the payer were considered. RESULTS: A total of 59 patients were treated with afatinib for their EGFR mutation-positive advanced NSCLC; the median age was 61 years (range: 37-91). Performance status was zero in 61%, and brain metastases were present in 13.6%. Forty-four patients (74.6%) had a deletion in exon 19 only, while nine (15.3%) had a mutation in exon 21, 8 of them in L858R and one in L861Q. At a median follow-up of 41.8 months (95% CI 35.9-51.4), the median PFS was 14.3 months (95% CI 12.2-16.4), and the median OS was 29 months (95% CI 25.6-33.4). Corresponding values for patients with deletion 19 only were 14.3 months (95% CI 11.5-18.5) and 28.1 months (95% CI 21.1-32.6), respectively. The mean expenditure for the treatment of each patient equals €25,333.68; with €21,865.06 being attributed to drug acquisition costs, €3325.35 to monitoring costs and €143.27 to adverse event treatment-related costs. CONCLUSION: Long-term data in the real-world setting in Greece confirm activity, tolerability and cost-effectiveness of afatinib as first-line treatment of patients with advanced EGFR-mutant NSCLC. CLINICAL TRIAL REGISTRATION: Clinicaltrials.gov NCT04640870.