: Temporomandibular disorders (TMD) are a heterogeneous group of musculoskeletal and neuromuscular diseases involving the temporomandibular joint complex and the surrounding muscle and osseous structure. TMD can be classified as intra-articular or extra-articular. The aim of this study was to evaluate the effect of arthrocentesis in terms of maximum mouth opening (MMO) and pain in patients with TMD of intra-articular origin. In addition to this treatment, the effects of factors such as splints, medication, and physical therapy on arthrocentesis were examined. : This retrospectively designed study was conducted with 79 patients who had previously undergone arthrocentesis. These patients were divided into three groups according to the Research Diagnostic Criteria for temporomandibular disorder: disc displacement (DD) with locking (Group 1), DD without locking (Group 2), and degenerative joint diseases (Group 3) groups. The maximum mouth opening (MMO) and visual analog score (VAS) values of the groups were recorded before arthrocentesis (Baseline: T0), on the third day after arthrocentesis (T1), and at the sixth month (T2) after arthrocentesis. Information about whether the patients received concurrent medical treatment, splint treatment, and physical therapy was also recorded. These data were compared between groups. : It was observed that the VAS scores in all three groups decreased from T1 compared to T0 ( < 0.05). Likewise, the MMO value increased in all groups at T1 compared to T0. ( < 0.05). It was observed that splint treatment, pain killer and muscle relaxant treatment, and physical therapy made no additional contribution to arthrocentesis in terms of reducing pain or increasing MMO value ( > 0.05). : Arthrocentesis was observed to be effective in terms of pain and function in TMJ patients in this study. It was observed that splint therapy, physical therapy, and medical therapy made no additional contribution to arthrocentesis in terms of MMO or pain.