Connective tissue diseases represent a heterogeneous group of immunologically mediated inflammatory disorders with a large variety of affected organs other than the lung. (18)F-fluorodeoxyglucose positron emission tomography ((18)F-FDG PET) is widely used in oncology but may also be valuable in patients with infections or inflammatory disease. The purpose of this article was to assess the clinical value of (18)F-FDG PET in patients with connective tissue disease. Our experience demonstrates that (18)F-FDG PET is a unique imaging technique for assessing the metabolic activity throughout the body in those with a connective tissue disease. The technique appears to be a promising imaging modality for detecting coexistent neoplastic diseases and other autoimmune disorders.