Fluorodeoxyglucose (FDG) PET imaging of arthritis is still in its infancy. Neither the optimal methodology nor the real clinical value is known at this time. Nevertheless, initial results are highly encouraging and the feasibility of the technique is demonstrated. PET findings are correlated with results obtained with state-of-the-art MRI and ultrasonography as well as with established clinical assessment of rheumatoid arthritis. There are indications that FDG-PET may provide unique information regarding the prognosis and early response to treatment. The mechanism of FDG uptake in the diseased joints has to be clarified further, but the available data indicate that it is well suited for imaging inflammatory joint disorders and, possibly, osteoarthritis. What lies ahead is the important work of clinical validation to verify the diagnostic and prognostic accuracy before envisioning a clinical role in routine practice.