A 52-year-old man, who was treated with antitubercular drugs for 1 year without any benefit for an initial diagnosis of tuberculosis, and was referred for further evaluation. An FDG-PET study was performed to evaluate the whole-body disease status, which showed multiple abnormal foci in bilateral neck nodes, mediastinal, axillary, and multiple abdominal (para-aortic and inguinal) nodes, and the liver, spleen, and thyroid. A rebiopsy of the inguinal nodes for a definitive diagnosis was confirmatory of sarcoidosis. He had a history of hypothyroidism, which is a frequent accompaniment of sarcoidosis due to the association of autoimmunity in this population. He was treated with oral corticosteroids and was referred for reassessment of his disease status with FDG-PET following 6 weeks of therapy. The FDG-PET images showed remarkable improvement with near total resolution of the FDG hypermetabolism at the initially involved sites. The present case underscores the value of FDG-PET imaging in whole-body monitoring of early response to therapy in patients of sarcoidosis (particularly those with extensive disease) that can be of substantial benefit and indicates the promise of this powerful molecular imaging technique in managing this multisystem disorder.