A positron emission tomography (PET) scan with 2-[fluorine-18]fluoro-2-deoxy-D-glucose ((18)FDG) was performed on a patient with clinical and laboratory signs of infection after a removed hip prosthesis but with indistinct signs on the bone scan and radiographs. The PET scan confirmed the clinical and laboratory signs and revealed an unidentified focus of infection in the distal area of the right femur.