Compulsive neuropsychiatric disorders are common in children and the most frequent is Gilles de la Tourette syndrome. Recently, a new disease has been described: the PANDAS syndrome (pediatric autoimmune neuropsychiatric disorders associated with streptococci). The etiology of this syndrome is uncertain but it has been associated with recent group A streptococcal infection (GAS). After an episode of pharyngitis, a boy aged 3 years and 9 months showed abrupt onset of a variety of neurobehavioral problems such as tics (consisting of elevation of the head and ipsilateral shoulder, winking, and grimaces) and compulsions (such as repeatedly hitting objects). A complete biochemical study was performed, including Cu and ceruloplasmin (which had normal values), antistreptolysin O (ASLO) and anti-DNAse (showing elevated values). Pharyngeal culture revealed GAS. The child was initially treated with valproic acid, but his subsequent improvement coincided with penicillin treatment for 10 days. Three months afterwards, ASLO values were reduced and at the 6-month follow-up the improvement was maintained even after suspension of valproic acid. Immunohistochemical studies were requested. PANDAS syndrome was first described in 1998 in a group of children who presented 1) obsessive compulsive disorders and/or tics, 2) episodic course with abrupt exacerbations, 3) abnormal results of neurologic examination (choreiform movements), and 4) temporal relation between GAS infection and onset of symptoms. The etiology of this syndrome is unclear, and it has been postulated that certain streptococcal antigens trigger antibodies which, through a process of molecular mimicry, cross-react with epitopes on the basal ganglia of susceptible hosts, such as the B8/17 antigen, among others. Current recommendations include penicillin treatment of each exacerbation with positive throat culture, and more aggressive therapies (intravenous immunoglobulin or plasmapheresis) when symptoms are severe. We believe that the case presented herein is a probable PANDAS syndrome, which would be the first case described in Spain.