Twenty-two patients (29 joints) with temporomandibular joint (TMJ) arthritis of specific or unspecific nature were given one intra-articular glucocorticoid (GC) injection. The effect on subjective symptoms and clinical signs in the craniomandibular system and on joint aspirate concentration of neuropeptide Y-like immunoreactivity (NPY-LI) was evaluated at follow-up visits 2-3 or 4-6 weeks after treatment. In the patients with specific inflammatory joint disease the treatment resulted in an improvement of symptoms and clinical signs and in a reduction in the TMJ level of NPY-LI 2-3 weeks after treatment. In the patients with unspecific inflammatory joint disease there was also an improvement in the clinical variables and a reduction in the NPY-LI level after 2-3 weeks, but not on a statistically significant level. The results of this study show that intra-articular GC treatment causes a short-term decrease of the TMJ fluid level of NPY-LI in patients with specific inflammatory joint disease, while symptoms and signs improve.