Disease activity assessment in large vessel vasculitis (LVV) is often challenging for physicians. In this study, we compared the assessment of disease activity based on inflammatory markers, clinical indices (Indian Takayasu Activity Score [ITAS] and the Kerr/National Institute of Health indices [Kerr/NIH]), and 18F-Fluorodesossiglucose (FGD) vascular uptake at positron emission tomography (Pet). We found that Pet results did not statistically correlate with the clinical indices ITAS and Kerr/NIH, because FDG uptake was increased (grade>2 on a 0-3 scale in at least one evaluated vascular segment) in many patients with inactive disease according to clinical and laboratory parameters (i.e., negative ITAS and Kerr/NIH indices as well as normal erythrocyte sedimentation rate (ESR) and C-reactive protein (PCR)). Similarly, interleukin- 6 and its soluble receptor did not statistically correlate with disease activity. In contrast, clinical indices showed a significant correlation between each other and with inflammatory markers (VES and PCR). These data suggest that while clinical indices and inflammatory markers may be useful to assess disease activity, Pet may be more sensitive.