Abstract: Paroxysmal kinesigenic choreoathetosis（PKCA）is a rare involuntary movement disorder. Attacks are induced by movemen or startle. The movements are tonic, dystonic or choreoathetotic. Sporadic or more commonly familial cases have been reported. Onset occurs most often during childhood and the course is nonprogressive. Response to anticonvulsant therapy is usually excellent. In this paper, four cases （2 in familial form and two in sporadic form） were reported. The attacks in all these 4 patients were induced by sudden movements, such as rising from the chair. on running and so on. Physical examinations and laboratory studies including EEGs and CT scans of the head were entirely negative in all 4 patients. The attacks ceased in two of four patients after the treatment with phenytoin.