Background: Tuberculosis (TB) is one of the commonest infectious diseases of our era; it is the second cause of death due to infectious diseases after AIDS. Studies have shown the significant effect of leukocyte integrins such as LFA-1and ICAM-1 on the function of macrophages against TB bacilli; increasing their activity during the process of TB infection. The objective of this research is to evaluate the changes observed in serum levels of SICAM-1 in pulmonary TB patients that had received treatment. Materials and Methods: All new pulmonary TB cases that had not received any treatment ,did not suffer from any kind of co-existing or underlying disorders such as hepatitis, sarcoidosis , lung cancer, HBV, HCV and HIV infections, chronic renal failure, cirrhosis, malnutrition, collagen vascular disorders and had not consumed immunosuppressive agents, were enrolled in this study. The SICAM-1 levels of the cases were measured by ELISA method before and 2 months after treatment with standard anti-TB drugs (Isoniazid, Rifampin, Ethambutol and Pyrazinamide) at the same time. T – test was used to compare the two sets of values of SICAM-1 levels before and 2 months after therapy. Results: A total of 28 patients; 23 (82.1%) male and 5(17.9%) female cases were enlisted .Meanwhile, 50% of the patients were Iranian and the remaining had Afghan nationality. All of them were sputum smear and culture positive for Mycobacterium tuberculosis. Regarding the extent of pulmonary involvement as shown on lung CT-Scan, 68% demonstrated diffuse pulmonary involvement. The mean SICAM-1 level before the initiation of treatment was 554.17 ± 202.85 ng/ml. Considering age , sex ratio, ESR level, PPD test and severity of lung involvement, the SICAM-1 levels did not show any significant differences in different groups of patients. Among the patients enrolled in the study we were able to follow the seventeen patients (61%) who completed 2 months of treatment. The mean level of SICAM-1 before and after treatment in these patients were 573.9 ±204.4 and 481.2 ± 103.2 ng/ml, respectively (p <0.05). Conclusion: SICAM-1 is considered as one of the inflammatory mediators that undergoes fluctuations during TB disease; its level is very much related to the extent of lung involvement. Since the level of this marker declines after therapy, it could be used as a "Serum marker "in evaluating the therapeutic response observed during the follow- up. Abbreviations: SICAM: Soluble Intercellular Adhesion Molecule, ICAM: Intercellular Adhesion Molecule, LFA: Leukocyte Function Antigen. (Tanaffos 2004; 3(11): 55-63)