Non-epileptic paroxysmal dyskinesias present with different forms of extrapyramidal hyperkinesias (dystonia, chorea, athetosis, ballism) in variable combinations and with cerebellar signs, respectively. They may be classified as: 1. paroxysmal dystonias/choreoathetoses (paroxysmal dystonic choreoathetosis = PDC), paroxysmal kinesigenic choreoathetosis = PKC, intermediate form) and 2. paroxysmal ataxias (PA) (PA with myokymia and neuromyotonia, azetazolamide-responsive PA). Nocturnal paroxysmal dystonia is now regarded as one form of nocturnal frontal lobe epilepsy. Research in molecular genetics has substantially contributed to the etiologic understanding of paroxysmal dyskinesias: In different families linkage has been successfully completed for PDC (chromosome 2q) and PA (chromosomes 12p, 19p). PA are now identified as channelopathies with mutations in the potassium channel (PA with myokymia and neuromyotonia) and the calcium channel gene (azetazolamide-responsive PA).