Objectives: Studying the expression of Cell adhesion molecules(CAM) 'ICAM-1, ICAM-3 and VCAM-1) in cases of acute appendicitis and the expression of IL-10 and IFN-gamma in situ to know the effect of those cytokines on the level of CAM expression , also to link those expression with histomorphological and clinical picture of the patients. Materials and Methods Thirty five acute appendicitis patients attending the emergency room in AL Kathumiyah Teaching Hospital were included in this study were diagnosed clinically and histopathologically from 1st of October 2003 to 30lh September 2004. 19 of them (54%) were males and 16 (46%) were females; their age range was (9-45 years). The control group was six patients suffering from blunt injuries by bullet or road traffic accidents or those with Colon cancer or advanced stages of ulcerative colitis or Croh's disease, taken as control tissue. Biopsies of patients and control appendices were taken and then fixed with formalin, and paraffin embedded, cut into tissue sections to study expression of Cell adhesion molecules and cytokines. Patients were classified according to Aschoff classification into : 8 (23%) with early acute appendicitis, 10 (28%) with acute Phlegmonous appendicitis, 6 (17%) with acute ulcerophlegmonous appendicitis, 5 (14%) were with acute gangrenous appendicitis, and histologically normal appendicitis who were 6 (17%) patients. The expression of Cell adhesion molecules was studied by the immunhistochemical technique which was suitable for tissues fixed by formalin and paraffin embedded in case of PECAM and VCAM or after antigen retrieval in case of ICAM-1 and ICAM-3, by the immunoperoxidase method which depends on avidin-biotin interaction. Also cytokines expression was studied using in situ hybridization method using long chain of cDNA probes specific for IL-10 and IFN-y. Results: Immunohistochemical study for CAM expression showed that ICAM-1 and VCAM expression was weak in control appendicies but this expression was higher in cases of acute appendicitis. While ICAM-3 was negative in control group but an increasing expression of that marker was observed in cases of acute appendicitis. In situ hybridization of cytokines showed that the percent of cells expressing mRNA of IFN-y or IL-10 in control group were less than that of patients and the percent of cells expressing IFN-gamma was increasing with advanced cases of acute appendicitis. Conclusions From these findings we can conclude that there are significant differences in the degree of expression and number of expressing cells for CAM between the normal tissue and tissue from acute appendicitis patients and that level of expression and number of cells expressing those markers is increased with the shifting of cases from early acute tppendicitis to gangrenous appendicitis. Also that the expression of CAM WIS dependant on the balance between the Level of IL-10 and IFN-y Specially after 12.5 hours from first symptom and IFN-y is the main player in that balance, whenever its level is increased there will be ihifting of the clinical condition into a more advanced stage by increasing the expression of CAM. As a result there will be increased infiltration of Inflammatory cells.