INTRODUCTION: Osteoarthritis is one of the most common degenerative diseases affecting the joints. Adjuvant- induced arthritis (AIA) is an experimental model of polyarthritis which has been widely used for preclinical testing of several anti-arthritic agents and investigating the pathogenesis of arthritis. A modified model of AIA was used in this study, where the disease was induced in one joint. Hyaluronic acid deals with the degenerative effects of arthritis from 3 different aspects: mechanically by maintaining lubrication, metabolically by providing nutritional materials to the articular disc and biologically by decreasing inflammatory effects. OBJECTIVES: to study the biochemical actions of high molecular weight hyaluronic acid (HMWHA) in management of temporomandibular joint (TMJ) adjuvant induced arthritis by detecting matrix metalloproteinase-3 (MMP3) concentration in TMJ tissue extract. MATERIALS AND METHODS: 14 male albino rats were divided into 2 equal groups and in each group a split mouth design was used. •Study I: Arthritis was induced in 7 animals through a single intra-articular injection of Complete Freund's Adjuvant (CFA) in the left TMJs. (50µl) •Study II: Arthritis was induced in the other 7 animals through a single intra-articular injection of CFA and treated with an intra-articular injection of HMWHA into their left TMJs, once a week for total of three injections. 7 animals were sacrificed on day 7 of the disease while the other 7 animals were sacrificed one week after the last injection of HMWHA. Elisa test was performed to detect MMP 3 which is considered as a biomarker of the disease progression RESULTS: The concentration of MMP-3 of study I (diseased group) on day 7 was found to be significantly higher than that of study II (treated group) on day 28. CONCLUSIONS: High molecular weight hyaluronic acid is capable of management of osteoarthritic TMJs.