The Castleman disease was described for the first time in 1956 by Castleman. It is a rare disease of the lymphatic tissue, manifesting in excessive proliferation of lymphocites B and plasmatic cells in lymph nodes. The etiopathogenesis if the disease still is unknown. The paper presents a case of the Castlemana disease (hyaline vascular type) in 20-year-old man with unilateral enlargement of neck lymph nodes. The case exemplifies the difficulties met in diagnostics and treatment of the Castleman disease.