The aim is to report our observations regarding the role of F-18 FDG PET in children's infectious processes.A presentation is made of 3 neonatal infections unresponsive to treatment, 2 invasive infections in immunocompromised children, and 1 discitis in an immunocompetent child. PET or PET/CT was performed to address a specific question pertaining to the management of the diseases. Results were correlated with the clinical outcome. The impact on patient management is discussed.In 1 neonate, PET localized the infection in a bone which allowed surgical curettage. In another one, it localized the infection in recently renewed exogenous material and led to subsequent removal. It was negative in the third one, whose evolution was rapidly favorable. In the immunocompromised children, treatment of invasive infection was adapted according to the metabolic inflammatory activity of the disease. In a limping child with slight abnormalities on bone scintigraphy but major misleading involvement on MRI, PET/CT demonstrated hypermetabolism limited to a disc, thus avoiding further invasive procedures.Although not meant as a first choice examination, F-18 FDG PET should be considered in difficult cases of neonatal infection or in challenging diagnoses like discitis in the young child. It provides more accurate staging and treatment monitoring of the inflammatory process in invasive infections of immunocompromised children.