A patient aged 67 had suffered from hypoparathyroidism (tetany and cataracts) following thyroidectomy at the age of 20, although treated with AT 10. During the last few years there had been a change of gait to small steps and general retardation. Nocturnal epileptic attacks occurred in the last year which led to the admission to hospital where a well developed parkinsonian syndrome without tremor was observed. X-rays of the skull, including computed tomograms, revealed calcification of the basal ganglia and dentate nuclei. Treatment with levodopa was ineffective. The mechanism for this is discussed.