Recently, abnormal expression of a great variety of adhesion molecules has been reported in malignancy. Of these adhesion molecules, intercellular adhesion molecule-1 (ICAM-1) has been suggested to play an important role in the process of tumor invasion and distant metastasis. The purpose of this investigation was to assess the peripheral blood levels of soluble ICAM-1 and the effect of cytotoxic therapy upon these circulating molecules in a cohort of patients with lung cancer. This study comprised 19 lung cancer patients hospitalized in our institution (males 16 and females 3, mean age 60 years old). Serum concentration of soluble ICAM-1 was measured using a commercially available enzyme immunoassay test kit. These measurements were done before the initiation of any therapy and on day 5 of chemotherapy. Samples taken from healthy volunteers were available for comparison. Soluble ICAM-1 serum concentration was significantly higher (p < 0.0001) in the cancer patients as compared to that of the control group. Serum levels of ICAM-1 were more significantly (p < 0.02) elevated in patients with advanced stages of disease. This study suggests the presence of an increased expression of circulating adhesion molecules in lung cancer. The concentration of this adhesion molecule was correlated with the clinical stage of the malignant disease, but did not change significantly after multidrug cytotoxic therapy.