The past decade has shed new lights on the cause and treatment of articular disorders (mainly, internal derangement) of the TMJ. However, the exact cause of ID is still unknown. It has been thought that the pathophysiology of disc displacement is multifactorial and complex.It is believed that arthrocentesis may bridge the gap between conservative therapy and invasive surgical treatment. Since Opiates behave like cytokines, modulating the immune response by interaction with their receptors in the central nervous system and in the periphery. Morphine was used in this study to measure its outcome and its effect on TNF level. Eighteen out of the thirty two selected patients with a clinical diagnosis of internal derangement (fifty six %) did not respond to conservative therapy for at least one month were included in this study. Two patients in group A and seven patients in group B reported their need for analgesics within the first twenty four postoperative hours indicating an analgesic effect of morphine. Within each group significant reduction in pain and dysfunction was found throughout the study intervals the results of thesynovial analysis were different within the group group A showed a statistically significant decrease in mean TNF-α after one week and through the whole study period (Pre-operative – three months) while in group B, there was no statistically significant change in mean TNF-α through all periods.