Thirty patients with necrotizing lymph-adenitis, a disorder initially described in Japan and commonly misdiagnosed as malignant lymphoma, have been studied, in addition, stains for immunologic markers were performed. The patients included 21 United States residents and most commonly were young women with a subacute illness characterized by persistent, painless cervical adenopathy with or without fever. The excised lymph nodes were moderately enlarged and typically showed focal, well-circumscribed, paracortical, necrotizing lesions, and abundant karyorrhectic debris, scattered fibrin deposits, aggregates of large mononuclear cells, and a paucity of plasma cells and neutrophils. Immunohistochemical stains on frozen tissue sections were positive for 63D3 and Leu-2a, indicating an admixture of of histiocytes/macrophages and cytotoxic/suppressor T-lymphocytes in the necrotizing lesions. The etiology of necrotizing lymphadenitis and its distinction from other causes of reactive lymphadenitis are discussed. To our knowledge, this disorder has not previously been reported in the United States.