Twenty-three children and 52 adults with torsion dystonia of various etiologies and distribution patterns of the involuntary movements were treated in an open-label study with anticholinergic medication. The dosage was increased gradually until there was either benefit or intolerable adverse effects. Trihexyphenidyl was used initially, but later ethopropazine was given to adult subjects. Significant benefit occurred in 61% of children and in 38% of adults. The average daily dosages were 41 mg trihexyphenidyl for children, 24 mg trihexyphenidyl for adults, and 350 mg ethopropazine for adults. Adverse effects were the major limiting factor to high dosage in adults, but not in children.