Castleman's Disease (CD) is an uncommon and poorly understood disorder of lymph node hyperplasia of unknown etiology. This entity belongs to the atypical lymphoproliferative disorders, a heterogeneous group of diseases characterized by a hyperplastic reactive process involving the immune system. The association of the nephrotic syndrome and CD is extremely rare and their interrelation remains enigmatic. We report a case of CD of the hyaline-vascular type with unicentric localization complicated by nephrotic syndrome.