Progressive weight loss, common reduces performance and quality of life in patients with advanced lung cancer. However, there is a paucity of studies that focus on nutritional status and quality of life of non-small cell lung cancer (NSCLC) patients. The present study seeks to determine the nutritional status, and its relation to quality of life, of NSCLC patients. One hundred and eighty NSCLC patients (mean age 62.8 ± 9.6 years) were evaluated during therapy at the Lower Silesian Center of Lung Diseases in Wroclaw, Poland. Nutritional status was evaluated by means of the Mini-Nutritional Assessment (MNA) and quality of life by means of two instruments developed by the European Organization for the Research and Treatment of Cancer (EORTC): QLQ-C30 and QLQ-LC13 questionnaires. The MNA revealed that up to 51.1% of patients were undernourished, 23.9% were at risk of malnutrition, and only 25.0% showed a normal nutrition. The well-nourished respondents evaluated their quality of life better in all functional scales (33.3 vs. 41.7 vs. 66.7, respectively) and presented less intensive symptoms in general QLQ-C30 and specific LC13 questionnaires. In univariate analysis, malnutrition significantly correlated with decreased quality of life and the intensity of symptoms in both questionnaires. In multivariate analysis, malnutrition was an independent determinant of decreased quality of life in physical functioning domain (β = -0.015; p < 0.001). We conclude that malnutrition has an impact on quality of life and on the presentation of symptoms in NSCLC patients. Therefore, nutritional care should be integrated into the global oncology as an adjunct to symptomatic treatment.