We present a 30-year-old woman with a medical history of McCune-Albright Syndrome who underwent an F-18 FDG-PET scan for further evaluation of cervical adenopathy noted on a recent computed tomographic examination. Intensely hypermetabolic foci were noted in the axial and appendicular osseous structures, correlating with foci of polyostotic fibrous dysplasia seen on CT scan. Increased uptake of Tc-99 MDP or HDP in polyostotic fibrous dysplasia is well described. The potential for misdiagnosis of intensely hypermetabolic foci involving fibrous dysplasia on F-18 FDG-PET scan has also been described. This is a rare case of FDG-PET hypermetabolism of polyostotic fibrous dysplasia in the setting of McCune-Albright Syndrome.