The level of the acute-phase response is a major predictor of survival in patients with advanced pancreatic cancer. This study examines the association between the acute-phase protein response, as determined by serum C-reactive protein, and serum levels of interleukin-6, soluble interleukin-6 receptor and the soluble tumour necrosis factor receptors in patients with pancreatic cancer. Thirty-four blood samples were collected from 13 patients with advanced pancreatic cancer. Samples were also collected from six healthy subjects. Levels of C-reactive protein, interleukin-6, soluble interleukin-6 receptor and soluble tumour necrosis factor receptors 55 and 75 were measured by indirect ELISA. Serum levels of C-reactive protein, interleukin-6 and soluble tumour necrosis factor receptors 55 and 75 were significantly higher in cancer patients than in controls. Levels of serum soluble interleukin-6 receptor were not significantly different between the two groups. In cancer patients, a significant positive association was found between the level of the acute-phase protein response and serum levels of interleukin-6, soluble tumour necrosis factor receptor 55 and soluble tumour necrosis factor receptor 75. No association was found between levels of soluble interleukin-6 receptor and any other factor. There is no significant relationship between the level of soluble interleukin-6 receptor and the acute-phase protein response in vivo and the biological role of soluble interleukin-6 receptor in the chronic inflammatory component of cachexia remains unclear.