In addition to preventing tissue energy loss during cardiopulmonary bypass. pentoxifylline (Ptx) prevents the production of pro-inflammatory cytokines as well. The aim of this study was to investigate whether Ptx decreases the inflammatory effects of cardiopulmonary bypass on the lungs during open-heart surgery, The patients in the study group (n=15) who were going through an open-heart surgery had 500 mg l(-1) of Ptx added to their prime solution, whereas the patients in the control group (n=10) only received prime solution. Pre-pump and post-pump blood samples were obtained from both groups and assayed for intereukin-6 (IL-6), interleukin-8 (IL-8) and tumour necrosis factor alpha (TNFalpha), Lung tissue samples that were obtained after the pump were examined with light microscopy and stained for tissue TNFalpha Non-parametric Wilcoxon test was utilized for statistical evaluation, In the post-pump period, the difference in the IL-6, IL-8 and TNFalpha levels of the two groups was found to be statistically significant (P < 0.005). The tissue samples from the control group had significant staining with TNFalpha. We think that Ptx has important protective effects on the lungs during cardiopulmonary bypass. (C) 2002 Elsevier Science Ltd.