We present a case of cat-scratch disease in a 9-year-old girl, complicated by encephalopathy and seizures. Bartonella (formerly Rochalimaea) henselae is the causative agent in cat-scratch disease; methods now available for detection of this pleomorphic, gram-negative bacterium, including polymerase chain reaction amplification and indirect fluorescence antibody testing, may lead to changes in standard criteria used to verify a diagnosis of cat-scratch disease.