Two boys who were immobilised with peripheral neuropathy developed hypercalcaemia. It is suggested that hypercalcaemia aggravated the muscle weakness as well as producing systemic upset. The hypercalcaemia was controlled with corticosteroids which had to be continued over several months. A satisfactory remission of the disease occurred in both cases. The hypercalcaemia was attributed to immobility in young people with rapid calcium turnover in bone.