Sinus histiocytosis with massive lymphadenopathy (Rosai–Dorfman disease) being a rare benign proliferative self-limiting disease of the cells of macrophage-histiocyte family is of unknown etiology and presents with massive lymphadenopathy. We are hereby reporting a case of RDD presenting with massive bilateral cervical and submandibular lymphadenopathy, diagnosed by histocytopathology.