The natural history of early onset idiopathic torsion dystonia in 30 young patients is reported from the Instituto Neurologico “C. Besta”, Milan, Italy. Twenty-one were sporadic and nine familial. Of the familial cases, eight had an autosomal recessive hereditary pattern and one an autosomal dominant pattern. All were of European origin and none were of Jewish origin. Quantitative criteria and a dystonic severity scale were used. Drug trials in eight patients were without benefit and stereotactic thalamotomy in ten patients relieved a unilateral action tremor. Age at onset ranged between one and ten years, maximum between five and ten years. An abnormality of gait was the presenting sign in 12. The disease became generalized in 17 and remained localized in 13. Early onset was characterized by a spontaneous tendency toward a stabilization of the motor disability following aggravation of the disability during the first seven years of the disease. Most retained functional independence and none showed mental deterioration, mood alteration or personality disturbance. The mean IQ in familial cases was 73.4 compared to 94.9 in sporadic cases. [1]