A Phase 2, to Evaluating the Safety and Efficacy of Pridopidine Versus Placebo for Symptomatic Treatment in Patients With Huntington's Disease

Inclusion Criteria:

- Diagnosis of HD based on the presence of >/= 36 CAG repeats

- Male or female age ≥21 years, with an onset of HD after 18 years' old.

- Females of child bearing potential have to be compliant in using adequate birth
control throughout the duration of the study

- Body weight ≥50 kg

- Sum of >/= 25 points on the UHDRS-TMS and UHDRS Independence Score below 90%

- Able and willing to provide written informed consent prior to any study related
procedure.

- Willing to provide a blood sample for genetic analyses

- Willing and able to take oral medication and able to comply with the study specific
procedures.

- Ambulatory, being able to travel to the study centre, and judged by the investigator
as likely to be able to continue to travel for the duration of the study.

- Availability and willingness of a caregiver, informant or family member to accompany
the patient to the clinic at study, and the suitability of the caregiver should be
judged by the investigator.

- Other criteria apply, please contact the investigator for more information.

Exclusion Criteria:

- Patients with clinically significant heart disease at the screening visit

- Treatment with tetrabenazine within 6 weeks of study screening

- Patients with a history of epilepsy or of seizures within the last 5 years

- Have other serious medical illnesses in the opinion of the investigator may put the
patient at risk when participating in the study or may influence the results of the
study or affect the patient's ability to take part in the study

- Patients receiving medications (within the last 6 weeks prior to screening) that have
been proven to prolong QT interval or who may require such medications during the
course of the study such as but not limited to non allowed anti psychotic medications,
tricyclic antidepressants and/or Class I antiarrhythmics

- Patients receiving medications (within the last 6 weeks prior to screening) that are
metabolized by CYP2D6 and have the potential of reducing seizure threshold

- Other criteria apply, please contact the investigator for more information