INTRODUCTION: Lung cancer (LC) is the first cause of cancer-related mortality worldwide and health-related quality of life (HRQL) is a fundamental outcome for evaluating treatment results. Our objective was to validate the Mexican-Spanish versions of the European Organisation for Research and Treatment of Cancer (EORTC) Quality-of-Life QLQ-LC13 disease-specific questionnaire module in Mexican patients with LC; and to explore the possible prognostic role of HRQL data. METHODS: Translation procedures followed EORTC guidelines. Both instruments were completed by patients with LC. Tests for reliability and validity were performed. A subset of patients was administered HRQL evaluations before and after chemotherapy. HRQL was associated with prognosis in chemotherapy-naïve patients. The protocol was approved by the Institute's Ethics Committee. RESULTS: One hundred fifty three patients (mean age, 60.3 years; 84 females and 69 males) completed both questionnaires. Compliance rates were high, and the questionnaires were well accepted. Nine of 10 multi-item scales of both questionnaires presented Cronbach's alpha coefficients > 0.7. Multi-trait scaling analysis demonstrated good convergent and discriminant validity. Patients with better Karnofsky or Eastern Cooperative Oncology Group (ECOG) performance status reported better functional HRQL scores. Different scales in the EORTC QLQ-C30 and EORTC QLQ-LC13 questionnaires were accurately related with clinical characteristics. Functional as well as disease-symptom scales improved after chemotherapy, but treatment side-effects scales worsened in test-retest analysis. Better role functioning and absence of thoracic pain scales were associated with longer overall survival (OS) (p = 0.009 and p = 0.035, respectively). CONCLUSION: The Mexican-Spanish versions of the EORTC QLQ-C30 and EORTC QLQ-LC13 questionnaires are reliable and valid for HRQL measurement in Mexican patients with LC and can be used in clinical trials.