An impairment of in vitro cytotoxicity and tumoricidal function of alveolar macrophages (AMs) in patients with lung cancer was reported in a number of studies. The aim of our study was to evaluate the expression of intercellular adhesion molecule-1 (ICAM-1) on AMs after stimulation with interferon-gamma (IFN-gamma) in patients with non-small cell lung cancer (NSCLC). The study was performed in 13 patients with NSCLC, 6 patients with various nonmalignant pulmonary diseases, and 6 healthy volunteers. AMs were isolated from bronchoalveolar lavage fluid (BALF) by adherence and then cultured with or without IFN-gamma for 24 h. The expression of ICAM-1 on AMs was analyzed by flow cytometry. Stimulation with IFN-gamma caused increased expression of ICAM-1 on AMs in all studied groups (p < 0.05). The degree of the increase in ICAM-1 expression on AMs after IFN-gamma stimulation was significantly lower in patients with NSCLC compared with healthy volunteers (p = 0.002) or the other patients (p = 0.022). The results suggest impaired reactivity of ICAM-1 expression on AMs after stimulation with IFN-gamma in patients with NSCLC, which might be involved in functional defects of AMs in patients with NSCLC.