Literature on psychiatric manifestations of hyperparathyroidism published in the last four decades confirms the unusual features of a case of paranoid psychosis secondary to a parathyroid-adenoma-induced hypercalcaemia. Affective and organic symptoms are overwhelmingly dominant in hypercalcaemic patients; the majority of cases reported are women of 50 years or older, who have been vaguely ill for a prolonged time before the actual endocrinopathy appears. The severity of the psychiatric symptoms does not seem to be related to the degree of hypercalcaemia. Recent findings link the role of calcium and related ions in the production of psychopathological symptoms to membrane phenomena, dopaminergic activity, and neuroendocrine regulation.