Background: The OPTIMAL study demonstrated significant superiority for E versus GC in terms of progression-free survival (PFS), objective response rate, tolerability and quality of life (QoL) in first-line advanced NSCLC patients with EGFR activating mutations (Act Mut+). Here we report OS data from OPTIMAL (ClinicalTrials.gov NCT00874419). Methods: Chemotherapy-naive Chinese patients with advanced NSCLC and EGFR Act Mut+, ECOG performance status (PS) 0–2 and measurable disease were randomized to E (150 mg/day), or GC, and stratified by histology, smoking status and mutation type. OS at final data cut-off (15 Nov 2011) was evaluated for the entire intent-to-treat (ITT) population. Subgroup analysis of OS by gender, histology, smoking status, PS, presence of skin rash and type of mutation was performed. Details of second- or later-line therapy were also documented for each patient. Results: A total of 165 patients were randomized to treatment and 154 patients received at least one dose of study drug (ITT population; E, n=82; GC, n=72). A total of 7 patients are still responding to erlotinib in the E arm. Post-study therapy included chemotherapy (doublet, n=38, or mono, n=8), or experimental drugs in clinical trials (n=10) in the E arm, and EGFR tyrosine kinase inhibitor (TKI) therapy (n=49) or chemotherapy (n=7) in the GC arm. Post-study treatment was not received by 26 and 16 patients in the E and GC arms, respectively. A total of 84 deaths were reported (E, n=47; GC, n=37). OS did not differ significantly between the two treatment arms (HR=1.065, p=0.6849), and no significant difference in OS was observed in the different subgroups. Conclusions: The lack of a statistically significant difference in OS in the OPTIMAL study was possibly due to a high level of cross-over to EGFR TKI therapy in the GC arm. However, the significant benefits reported with E in terms of PFS, QoL and tolerability in this study suggest that E should be considered as one of the standard first-line treatments for patients with advanced EGFR Act Mut+ NSCLC.