Florid necrotizing lymphadenitis, characterized by segmental infarction and lymphoid hyperplasia, is an uncommon feature of systemic lupus erythematosus (SLE). Kikuchi's disease is a well-defined clinicopathological entity, with a strong preference for the cervical lymph nodes of young women. The etiology of histiocytic necrotizing lymphadenitis (HNL) remains unknown, although viral agents have been proposed. HNL may reflect a self-limited SLE-like autoimmune disease but full-blown SLE associated with this condition has not, to the best of our knowledge, been reported. Thus, ours is the first description of the coexistence of SLE and HNL in 3 patients with immunologically proven parvovirus B19 infections. SLE and HNL were diagnosed simultaneously in 2 patients, but was retrospective in the third, in whom anti-tuberculous therapy was ineffective. Patients 1 and 2 were treated with prednisone (1 mg/kg/d) and responded rapidly. These data suggest that both HNL and SLE flares can be caused by parvovirus B19 infection.