This report presents clinical, laboratory, and neuroimaging findings in a 7-year-old male with Sydenham's chorea associated with attention-deficit hyperactivity disorder. Western immunoblotting revealed serum anti-human basal ganglia tissue antibodies. Magnetic resonance imaging results were normal. Proton magnetic resonance spectroscopic imaging disclosed increased choline/creatine ratio in basal ganglia, frontal, and parieto-occipital areas, and decreased N-acetyl aspartate/creatine ratio in both basal ganglia and frontal areas. Moreover magnetic resonance spectroscopy revealed a peak between 3.6-4.2 ppm of unclear significance. The findings of this study are compared with the previous magnetic resonance spectroscopic studies reported on Sydenham's chorea and attention-deficit hyperactivity disorder. Magnetic spectroscopic imaging suggests an autoimmune basal ganglia damage in the pathogenesis of Sydenham's chorea and fronto-striatal impairment in attention-deficit hyperactivity disorder. In the present case, the previous history of an attention-deficit hyperactivity disorder suggests that this neurobehavioral disorder could be a risk factor for Sydenham's chorea in children with rheumatic fever.