Interleukin (IL)-8 promotes cellular proliferation and angiogenesis in patients with non-small-cell lung cancer (NSCLC) and may be related to cachexia. Our aim was to investigate the relationship of IL-8 levels with nutritional status, and clinical outcome of patients with NSCLC. Patients with metastatic NSCLC referred for first-line therapy were eligible. Baseline IL-8 levels were measured in plasma. The Mini Nutritional Assessment (MNA) was used for the evaluation of the nutritional status, and patients were classified into 3 groups: A (score 24-30) "well nourished," B (score 17-23.5) "risk of malnutrition," and C (0-16.5) "malnourishment." Response to first-line chemotherapy, time-to-tumor progression (TTP), and overall survival (OS) were also recorded. In total, 114 patients (101 males, 88.5%; mean age = 67.5 yr) were evaluated. Performance status was 0-1 in 62% of the patients. According to the MNA, the majority of patients (71%) was either at nutritional risk or malnourished. IL-8 levels were significantly different between MNA groups (P = 0.023) and correlated with TTP (P = 0.013) and OS (P = 0.001) in univariate analysis. Baseline IL-8 levels correlate with the nutritional status of patients with metastatic NSCLC, suggesting that this cytokine may be related with cachexia.