This study examined the clinical and radiological effects of intra-articular tenoxicam injection following arthrocentesis and compared them with arthrocentesis alone in patients with disc displacement without reduction (DDwoR). 24 temporomandibular joints (TMJs) in 21 patients with DDwoR were studied. Patients were divided randomly into Group A in which only arthrocentesis was performed (14 TMJs in 14 patients) and Group AT which received arthrocentesis plus intra-articular injection of tenoxicam (10 TMJs in 7 patients). Patients were evaluated before the procedure, on postoperative day 7, then 2, 3, 4 weeks, and 2, 3, 4, 5, 6 months postoperatively. Intensity of joint pain was assessed using a visual analog scale. Maximum mouth opening was recorded at each follow-up. TMJ sounds and palpation scores were noted as positive or negative. Magnetic resonance imaging (MRI) was performed before and 6 months after treatment in both groups. Disc form, disc location during neutral position, reduction with movement, joint effusion, structures of the articular surfaces, and bone marrow anomalies were evaluated all in MRIs. Both treatments succesfully increased maximum mouth opening and reduced TMJ pain; there were no complications. Difference between the groups was not statistically significant and a larger controlled study is necessary to clarify this use of tenoxicam.