The present retrospective, single-center study evaluated the objective response rate (ORR) and progression-free survival (PFS) of epidermal growth factor receptor (EGFR) mutation-positive Malaysian patients with advanced lung adenocarcinoma treated with gefitinib. During May 2008 to July 2013, 33 patients with Stage IV, EGFR mutation-positive non-small-cell lung cancer (NSCLC) were identified and received gefitinib (250 mg) as first line treatment. The primary and secondary end points were ORR, PFS and safety, respectively. A total of 18 (54.5%) and 2 (6.1%) patients achieved partial response (PR) and complete response (CR) to gefitinib therapy, respectively, yielding an ORR of 60.6% (95% CI, 42.1-77.1%). Patients with exon 20 or 21 mutations (n=6, 66.7%) tended to have better ORR compared with exon 19 (n=22, 59.1%). The median PFS was 8.9 months in Malaysian patients with EGFR mutation-positive NSCLC, treated with gefitinib. The majority of treatment-related toxicity was mild in nature. The most frequently reported adverse events included dry skin (39.4%), skin rash (27.2%), and dermatitis acneiform (15.2%). In conclusion, Malaysian patients with locally advanced and metastatic EGFR mutation-positive NSCLC responded favorably to gefitinib therapy in terms of ORR, median PFS, and tolerability, the results of which were consistent with those of the IPASS study conducted in an Asian population. Considering the efficacy and safety profile of gefitinib, it is a favorable option for the first-line treatment of Malaysian patients with EGFR mutation-positive NSCLC. However, future long-term studies in a larger population of Malaysian patients are required to support whether the prolonged PFS conferred by gefitinib will translate into prolonged overall survival.