Background: Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcus infections (PANDAS) is a recently recognized syndrome in which pre-adolescent children have abrupt onsets of tics and/or obsessive-compulsive symptoms, a recurring and remitting course of illness temporally related to streptococcal infections, and associated neurologic findings including adventitious movements, hyperactivity and emotional lability. Methods: Inspired by observations of similar symptoms in children with Sydenham's chorea, a search was undertaken for clinical and laboratory evidence in support of the new syndrome. Results: Consistent and predictable clinical findings have been described in a large case series. Magnetic resonance imaging has supported the postulated pathobiology of the syndrome with evidence of inflammatory changes in basal ganglia. Antibasal ganglia antibodies have been found in some acute cases, mimicking streptococcal antigen epitopes. Conclusions: While PANDAS remains a controversial diagnostic concept, it has stimulated new research endeavors into the possible links between bacterial pathogens, autoimmune reactions, and neuropsychiatric symptoms.