METHODS: Twenty-six children age 4-15 years with cerebral palsy and dystonia that impairs function of the dominant upper extremity were enrolled. All children were given trihexyphenidyl at increasing doses over 9 weeks up to 0.75mg/kg/day. Trihexyphenidyl was subsequently tapered over 5 weeks. Visits occurred at baseline, 9 weeks, and 15 weeks. The primary outcome measure was the Melbourne assessment of upper extremity function, tested in the dominant arm.