Tumor necrosis factor (TNF)-alpha has been shown to induce shedding of ICAM-1. Experimental studies report that soluble intercellular adhesion molecule-1 (sICAM-1) may interfere with the host immunesurveillance system. Serum levels of TNF-alpha and sICAM-1 were determined by ELISA in 112 non-small cell lung cancer (NSCLC) patients. Serum concentration of TNF-alpha and sICAM-1 were related to tumor burden and progression; a significant correlation was observed between circulating levels of TNF-alpha and sICAM-1. Our study suggests that ICAM-1 could be a marker of TNF-alpha activity and that high levels of these molecules may have a prognostic value in lung cancer.