Paroxysmal kinesigenic choreoathetosis (PKC) is characterized by episodes of brief dystonia or choreoathetosis which is induced by sudden movement. We report the clinical manifestations and efficacy of treatment with carbamazepine in familial PKC. Seven patients from two families were diagnosed with PKC. The most common precipitating factors in our patients were sudden movement, anxiety and stress. The mean age of the first attack was around early puberty, and the symptoms became remarkable during early adulthood. Interictal single-photon emission computed tomography of the brain revealed abnormal perfusion of regional cerebral flow in either the basal ganglia or thalami in most of the patients. Four of seven patients were prescribed low dose of carbamazepine (1.5-2.0 mg/kg/day); the follow-up period ranged from 14 to 30 months. The patients who received carbamazepine treatment became attack-free without decline in school performance. The results suggest that the prognosis of PKC is a relatively benign entity due to spontaneous resolution since adulthood, and a low dose of carbamazepine is sufficient to manage PKC. Abnormal cerebral perfusion flow over the basal ganglia or thalami in these patients leads us to believe that PKC is a form of extrapyramidal disorder.