The prominent clinical manifestation of cat scratch disease is regional lymphadenopathy at the site of the cat scratch or bite, associated with fever or general symptoms. A serological study of 540 patients with either lymphadenopathy, persistent fever, or pet ownership disclosed that 30 (16.1%) of the 186 patients with a serological diagnosis of cat scratch disease had no regional lymphadenopathy, and in these 30 patients, the absence of lymphadenopathy was closely related to the presence of persistent fever, fever of unknown origin, or systemic complications. Physicians should be alert to cat scratch disease that is not associated with lymphadenopathy to enable prompt diagnosis and treatment.