In a patient with temporomandibular disorder who does not respond to conservative treatment, treatment with intra-articular injection of high molecular weight sodium hyaluronate can be suggested. In our study, 27 patients with nonreduced disc displacement were diagnosed clinically and confirmed by magnetic resonance imaging. The age range was from 21 to 63 years old, with a mean of 39.3 years. Two cycles of injection of high molecular weight sodium hyaluronate was performed on alternative weeks. Pain intensity was measured by the visual analog scale. Maximal mouth opening, clicking joint noise, and lateral movement were measured before and after injection for more than 6 months. Reduction of pain intensity and improvement in the maximum mouth opening parameter was statistically significant. In conclusion, this intra-articular injection using high molecular weight sodium hyaluronate looks very positive for patients affected by nonreduced disc displacement and is encouraged to be used as a primary treatment of temporomandibular joint dysfunction.