Abstract: As a newly identified systemic syndrome characterized by a high level of serum immunoglobulin G4(IgG4)and dense infiltration of IgG4-positive plasma cells into multiple organs including lacrimal gland, salivary gland, lung, pancreas, liver, biliary duct, kidney, prostate, retroperitoneum and so on, IgG4-related disease(IgG4-RD)has attracted growing attention recently. Timely and accurate diagnosis is an essential prerequisite for early intervention leading to better recovery and outcome in patients with IgG4-RD. 18F-FDG PET/CT has been served as an important imaging tool for patients with IgG4-RD in assessing organ involvement, guiding biopsy and monitoring therapeutic response. This review will summarize the state-of-the-art on applications of 18F-FDG PET/CT in patients with IgG4-RD.