We describe a case of 27 year-old female presenting with Kikuchi-Fujimoto's disease whose diagnosis was based on histopathologic and immunophenotypic studies. The illness was characterized by fever, urinary tract infections, skin rash, polyarthritis, generalized lymphadenopathy, pancytopenia, hepatic cytolysis and cholestasis, abnormal coagulation tests and elevated serum lactate dehydrogenase. The lymph node biopsy was consistent with the diagnosis of a histiocytic necrotizing lymphadenitis. Flow cyto-metric studies performed on the affected lymph node, bone marrow aspirate and peripheral blood, revealed a relative expansion of mature activated T lymphocytes, predominantly expressing a CD8 (+) phenotype.