Stereotaxic subthalamotomy of 55 patients with cerebral palsy gave a good result in 65% of the selected cases. The result was uncertain in 15 and poor in 20%. An independent socio-medical follow-up study confirmed the clinical finding. The more rapid the involuntary movements, the better was the effect of subthalamotomy. Intention tremor was the most suitable symptom for stereotaxic treatment. Rigidospasticity was alleviated in the distal muscles only. Speech and gait were often improved. Good results were obtained in patients with normal intelligence, while feeble-minded patients did not benefit from the operation. Subthalamotomy was followed by transitory side-effects in 20%, of which increased involuntary movements on the ipsilateral side and mental restlessness were the most frequent. The operation had no mortality. Spinal longitudinal myelotomy effectively relieved the spasticity of the lower limbs in the three patients operated upon.