ABSTRACT Objective: To translate the European Organisation for Research and Treatment of Cancer (EORTC) 29-item Quality of Life Questionnaire-Lung Cancer Module (QLQ-LC29, developed for the assessment of quality of life in patients with lung cancer) to Portuguese, conducting a pilot study of the Portuguese-language version and adapting it for use in Brazil. Methods: For the translation, cultural adaptation, and pilot testing of the QLQ-LC29, we followed the guidelines established by the EORTC. The translation (English → Portuguese) and back-translation (Portuguese → English) were both carried out by translators, working independently, who were native speakers of one language and fluent in the other. After review, a draft version was created for pilot testing in lung cancer patients in Brazil. Results: A total of 15 patients diagnosed with lung cancer completed the Portuguese-language version of the questionnaire. At the end of the process, we conducted a structured interview to identify any patient difficulty in understanding any of the questions. The final versions were sent to the EORTC and were approved. Conclusions: The Portuguese-language version of the EORTC QLQ-LC29 appears to be a useful, important, reliable questionnaire that is a valid tool for assessing quality of life in patients with lung cancer in Brazil.