A case is reported of hypomagnesaemia and hypocalcaemia occurring postoperatively in a 59-year-old man operated on for hypopharyngeal carcinoma which had extended to the upper extremity of the oesophagus. Surgery consisted in total pharyngolaryngectomy, ganglion curage, jejunal transplant, thyroidectomy and tracheostomy. Total parathyroidectomy was not mentioned in the surgical report. Hypocalcaemia was first noticed on the day following the procedure. On the tenth postoperative day, the patient became agitated and had myoclonia and muscle fasciculations. Nystagmus and orthostatic hypotension also occurred. There were no cardiac signs. Treatment with calcium alone was insufficient. These symptoms only disappeared once magnesium sulphate had been added.