Assessment of upper limb function, kinematic analysis, and dystonia in patients with spastic diplegia cerebral palsy and periventricular leukomalacia. Seven children with spastic diplegia cerebral palsy and 8 controls underwent upper limb kinematics. Movement duration, average and maximum linear velocity, index of curvature, index of dystonia, and target accuracy and stability were analyzed. In the patients with spastic diplegia, Gross Motor Function and Manual Ability Classification Systems were determined, and spasticity and dystonia were rated using the Modified Ashworth and the Burke-Fahn-Marsden Dystonia scales respectively. Children with spastic diplegia demonstrated a tendency toward higher index of dystonia reflecting overflow, higher index of curvature, lower velocities, and poor target accuracy and stability. All patients showed clinical evidence of dystonia in the upper limbs. Dystonia scores correlated with the Manual Ability Classification System (r = 0.86, P = .01) and with the index of dystonia (r = 0.82, P = .02). Children with spastic diplegia cerebral palsy present dystonia in the upper limbs. This is functionally relevant and can be measured with kinematic analysis.