IgG4-related disease (IgG4-RD) is a set of diseases that can affect multiple organs, produce an immune-mediated fibroinflammatory response, and lead to tissue destruction and organ failure. Hemophagocytic syndrome is a life-threatening hyperinflammatory fatal disease caused by defect and excessive macrophage activity in natural killer cells. The disease can often be confused with other immune-mediated diseases such as cancer, infection, interstitial lung disease, sjogren's syndrome, wegener's vasculitis, or temporal arteritis. Hemophagocytic syndrome is defined as hemophagocytic lymphohistiocytosis (HLH) which is a pathological and clinical condition caused by phagocytosis of erythrocyte, leukocyte, platelet and precursor cells which are the cellular elements of the macrophages which are activated due to various reasons. Although there are two types as primary (familial) and secondary (depending on infections), the clinical findings are the same. Presence of familial disease/known gene defect and/or at least 5 of 8 clinical and laboratory diagnostic criteria is required for diagnosis. The first target is the suppression of hyperinflammation urgently, the second is the elimination of the stimulus triggering the event. In secondary HLH, treatment should be planned according to the underlying cause. As a rare complication of a rare disease, a case with the diagnosis of IgG4-related disease complicated with hemophagocytic syndrome is presented with the literature.