Inclusion Criteria:

Patients will be included in this study if they meet the following criteria:

• Tourette syndrome criteria based on the TS Classification Study Group [1993], which includes onset before 18 years, multiple involuntary motor tics, one or more vocal tics, a waxing and waning course, the gradual replacement of old symptoms with new ones, the presence of tics for more than one year, the absence of other medical explanations for tics, and observation of tics by a reliable examiner;
• Age 7 to 19 years, either gender;
• Observable tics, achieving a minimum score of > 22 on the Total Tic score of Yale Global Tic Severity Scale (YGTSS);
• Tic symptoms severe enough to warrant therapy;
• The concurrent use of other tic-suppressing medications will be permitted, if the subject has been on a stable dose for more than three weeks and agrees to maintain a constant dosage throughout the study;
• Tics are not controlled with current medication or individuals are tic suppressing drug naive.

Exclusion Criteria:

Exclusion criteria include the following:

• Secondary tics;
• Significant medical illness
• Current major depression, generalized anxiety disorder, separation anxiety disorder, psychotic symptoms (based on clinical evaluation), pervasive developmental disorder, autism, mental retardation (I.Q. less than 70), anorexia/bulimia, or substance abuse. Subjects with co-morbid ADHD, obsessive compulsive disorder (OCD), and conduct disorder will not be excluded;
• pregnancy;
• Hypersensitivity to levetiracetam or clonidine;
• baseline weight of less than 25 kilograms.