Patients with degenerative disease of the temporomandibular joint (TMJ) who did not respond to conservative medical therapy (splint therapy, selected grinding or physiotherapy) can be treated by arthrocentesis, which is associated with intra-articular injections of sodium hyaluronate (Hyalgan). In this study, we treated ten dysfunctional patients with degenerative joint disease (DJD) who had been diagnosed clinically and had had the diagnosis confirmed by MRI. All subjects presented impaired mouth opening, joint pain at rest and on movement and impaired masticatory efficiency. We performed one cycle of five infiltrations with joint arthrocentesis and the injection of sodium hyaluronate at weekly intervals. The following parameters were assessed before and after infiltration and at follow-up after 6 months: mouth opening (with a mean of between 36.5 mm and 41.9 mm); sideways movements (to the right 4.9 mm to 8.9 mm and to the left 4.7 mm to 9.2 mm); pain at rest (VAS=1.8 to 0.5) and on movement (VAS=7.8 to 1.1); masticatory efficiency (VAS=5.7 to 8.6); subjective judgement of the functional TMJ limitation level (from 2.8 to 0.8); judgement of efficacy (from 2.4 to 3.2); judgement of tolerability to the therapy (from 2.0 to 3.1). The therapeutic benefits observed can be attributed both to joint arthrocentesis and to the characteristics of sodium hyaluronate itself. All the parameters considered revealed a statistically significant positive variation that persisted over time ( P<0.05). The results obtained by this minimally invasive, fast and easy technique proved to be valid and lasting. This infiltration technique using sodium hyaluronate looks very promising for patients affected by symptomatic DJD who do not respond to conservative medical therapy, reflecting similarly encouraging findings in the orthopaedic treatment of degenerative knee pathology.