The aim of this study was to determine the correlation between arthroscopically observed (ASC) changes in the synovial membrane and other joint components and synovial light microscopic (LM) findings in the temporomandibular joint (TMJ). Synovial membrane biopsies were obtained during unilateral arthroscopy in forty patients. Thirty-one patients were diagnosed with TMJ osteoarthritis (OA) and nine patients with non-osteoarthritic conditions of their TMJs. Correlations between ASC and synovial LM findings were analyzed with Cohen's Kappa and Spearman's rank correlation tests. Values for Kappa of 0.6 and higher and values for a correlation coefficient of 0.7 and higher were considered satisfactory. No correlations were found in the retrodiscal tissue biopsies. In the anterodiscal tissue biopsies, ASC hypervascularity correlated with LM intima cell shape and cell density. ASC lowered attachment to the anterior slope of the articular eminence correlated with the LM presence of a fibrous intima matrix. In several TMJs, a high concurrence was observed between ASC and LM pathologic changes. The severity of pathologic changes as observed by LM was, however, often less than was suggested arthroscopically.