Background: A frequent manifestation of advanced lung cancer is malnutrition, timely identification and treatment of which can lead to improved patient quality of life, response rate to chemotherapy and survival. N-3 fatty acids, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), may possess anticachectic properties. This trial compared a protein and energy dense supplement enriched with n-3 fatty acids with nutritional assessment for their effects on weight, lean body mass (LBM), body fat, phase angle, dietary intake, inflammatory response and quality of life in first-line chemotherapy patients with advanced lung cancer.