In order to test the serum levels of ICAM-1, ICAM-2 and ICAM-3 in patients with idiopathic pulmonary fibrosis (IPF), twenty patients with IPF and eleven with secondary interstitial fibrosis (SIF), as well as forty healthy volunteers (HV) were studied. Serum intracellular adhesion molecules (ICAM) 1, 2 and 3 were assessed by ELISA. Functional respiratory tests, which included spirometry and lung diffusing capacity were simultaneously performed. Median values of serum ICAM-1 and ICAM-2 were higher in the patients' than in the healthy volunteers' (HV) group: IPF group: 946.60 ng/ml and 400.14 ng/ml; SIF group: 901.58 ng/ml and 378.27 ng/ml; HV group: 308.40 ng/ml and 217.55 ng/ml, respectively (p<0.05). ICAM-3 serum levels were equal between the three groups. ICAM-2 negatively correlated to DLCO values. (p<0.005). It can be concluded that ICAM 1 and 2 are elevated in the sera of patients with pulmonary fibrosis. ICAM-2 might be associated with a more impaired clinical status.