Objectives: To assess the effect of gap arthroplasty surgery on immunocompetenceof patients with temporomandibular joint bony ankylosis in regard to salivary IgAand serum interleuklin-6.Materials and Methods: Twenty four subjects were selected and classified intotwo groups: Group I, comprised eight patients suffering from TemporomandibularJoint Bony Ankylosis (surgical group), and Group II, comprised sixteen healthysubjects as volunteers, related to, or neighbors of the selected patients andrepresented the (control group). Gap arthroplasty was performed on Group I eitherunilaterally or bilaterally under general anesthesia. Assessment of the effect of Gaparthroplasty on immunocompetence was achieved utilizing enzyme linkedimmunosorbent assay (ELISA) technique to attune Serum interleukin-6 andSalivary Immunoglobulin A which were utilized as parameters of assessment.Malnutrition was assessed through Anthropometric measurements and laboratoryanalysis of Serum Albumin and Serum Transferrin.Results: On comparison of preoperative mean value of IL-6 and sIgA betweengroup I and group II it was detected that there is a significant increase in the levelof IL-6 and a non-significant difference of sIgA level. On comparison of the meanvalue of serum IL-6 and sIgA postoperatively at different time intervals (one day,one week and three weeks) between the two groups, both calipers found to beincreased insignificantly.Conclusion: The present study revealed that patients of temporomandibular jointbony ankylosis have a significantly high level of serum IL-6 and gap arthroplastysurgery and its relevant jaw mobilization have a direct effect on immunocompetence in regard to increased level of IL-6 postoperatively. Salivary IgAincreased non-significantly in response to change of intraoral environment.