Purpose: The goal of this study was to evaluate the presence of the inflammatory cytokines interleukin-1β (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-α (TNF-α) within the superior temperomandibular joint (TMJ) space in patients with internal derangements and to compare these values with the pathologic findings seen arthroscopically. Patients and Methods: Thirty patients with symptomatic TMJ dysfunction and clinical and imaging evidence of internal derangements of the TMJ were evaluated. Before entering the superior joint space with the arthroscope, 2 mL sterile saline was injected and after 30 seconds of equilibration, was aspirated for analysis. The surgeon then performed diagnostic arthroscopy. The degree of synovitis, degeneration, percent condylar roofing, and any pathologic changes, such as perforations were recorded. The level of total protein in each sample was ascertained, as well as the levels of IL-1β, IL-6 and TNF- α. Results: Of 30 samples tested, three were discarded because of failure to gain access into the superior joint space. Of the 27 remaining samples, IL-6 showed the closest correlation with the level of acute synovitis demonstrated arthroscopically. Two of the higher IL-6 levels (167 and 324 pg/μg protein) were seen with patients with a significant disc perforation. In patients with a high degree of vascularity, IL-6 was found to be between 0 to 581 pg/μg protein with an average of 80 pg/μg protein and a median value of 43 pg/mg. These values significantly correlated with the degree of vascularity (P ≤ .02). This is in comparison with the 10 remaining patients, who showed significantly fewer vascular changes arthroscopically. In these patients, the range of IL-6 was 0 to 35 pg/μg protein, with an average of 19 pg/μg protein and a median value of 14.5 pg/μg. These values significantly correlated with the smaller degree of vascularity (P ≤ .02). In seven patients, the role of nonsteroidal antiinflammatory drug (NSAID) use resulted in decreased levels of IL-6, which has been noted in previous studies. In patients with higher rated redundancy of the synovial tissue, the average IL-6 level was 92 pg/μg protein, whereas the median value was 44 pg/μg protein. In patients with little or no redundant synovial tissue, an average IL-6 level of 22 pg/μg protein was present. The median value in these same joints was 15 pg/μg protein. These IL-6 values significantly correlated with the degree of redundancy (P ≤ .03). The degree of degenerative change (chondromalacia, fibrillation), disc displacement (roofing), and the presence or absence of adhesions did not significantly affect the levels of IL-6 within the patients studied. The presence of IL- 1β and TNF-α was not found to correlate with the arthroscopic findings in the superior joint space. Conclusions: The presence of IL-6 correlated with the degree of acute synovitis IL-1β, and TNF-α were not found in significant levels within the superior joint space. These findings correlated with those reported by other investigators. The production of IL- 6 by synovial cells and its role in TMJ disease warrants further investigation.