Antiphospholipids (aPLAs) have been previously identified in children with Tourette syndrome (TS), which has led to the speculation that these antibodies might have a pathophysiologic role in this disorder. Therefore, 21 healthy children and adolescents with TS, whose ages ranged from 7 to 17 years, underwent laboratory studies designed to diagnose the lupus anticoagulant, anticardiolipin (aCL) antibodies [immunoglobulin (Ig) G, IgA, and IgM], and antinuclear antibodies. Although five subjects had at least one value that differed from accepted laboratory standards, the changes were marginal in four of them. Lupus anticoagulant was identified in one patients, based on a minimal requirement of a prolonged dilute Russel viper venom time, clotting studies that did not correct after mixture with normal plasma, and an abnormal platelet neutralization procedure. A prolonged (but correctable) activated partial thromboplastin time was found in one individual, and aCL IgG was marginally increased in three subjects. Two (10%) of a control population of 20 same-age children also had low positive aCL IgG levels. There were no differences in tics (onset, type, frequency, severity, and family history) or comorbid features between children with normal or “abnormal” laboratory study results. Our data suggest that the presence of aPLAs in TS represents an epiphenomenon rather than a pathophysiologic mechanism.