The vast majority of pancreatic cancer patients have advanced disease at the lime of diagnosis and they eventually become se emaciated that death primarily occurs from cancer cachexia. Cancer cachexia may be mediated by certain cytokines such as interleukin-6. In this study we measured serum interleukin-6 levels in 55 patients with histologically proven pancreatic cancer and investigated their relationships to the clinical status of pancreatic cancer, A control population of 20 normal healthy adults and 25 chronic pancreatitis patients with comparable gender and age distribution characteristics was also studied. Serum interleukin-6 levels were measured using a quantitative sandwich enzyme-linked immunosorbent assay. Thirty pancreatic cancer patients (54.5%) had detectable levels, although interleukin-6 levels were detectable in only one healthy control and in two chronic pancreatitis patients. The specificity of serum interleukin-6 in this population was 93.3%, resulting in high diagnostic accuracy (72.0%). Among the pancreatic cancer patients, the detection rates of serum interleukin-6 levels increased significantly with the disease extent (p < 0.01), Moreover, a significant difference was also found in the detection Fates between the 30 pancreatic cancer patients with body weight lass (76.7%) and the remaining 25 patients without weight loss (28.0%, p < 0.01). These results may provide new insight ir-ito both diagnosis anal treatment of pancreatic cancer, because the diagnostic accuracy of serum interleukin-6 was high and because anti-interleukin-6 therapeutics could improve symptoms in pancreatic cancer patients with high interleukin-6 levels.