Hemiballism is a rare hyperkinetic movement disorder, characterized by irregular, wide amplitude and vigorous involuntary movements of the unilateral limbs. The term ballismus is derived from the Greek word meaning “to throw” because the abnormal movements resemble the motions of throwing. The movements are usually continuous but may be intermittent and can be voluntarily restrained by the patient, although only for a few minutes. They are most prominent during periods of rest but are absent during sleep.