A 59-year-old lady was admitted with lethargy and dehydration in October 1998 and investigations confirmed primary hyperparathyroidism with corrected calcium 4.49 mmol/l (N: 2.12.6). After fluid resuscitation, she underwent parathyroidectomy and biopsy revealed parathyroid hyperplasia. Post-operatively, her calcium remained normal until November 2000 when her corrected calcium was 3.05 mmol/l with PTH 311 ng/l (N: 1265). Sestamibi scan failed to localise parathyroid adenoma. In October 2001 she was admitted with severe hypercalcaemia 3.91 mmol/l and PTH 824 ng/l with good response to intravenous hydration. Repeat sestamibi scan was negative even with elevated corrected calcium levels (3.4 mmol/l). CT neck showed two intrathyroidal nodules and a left-sided mass behind the angle of the jaw. She underwent total thyroidectomy and removal of the additional neck mass with histology of the jaw mass confirming benign parathyroid adenoma. She remained eucalcaemic with mildly elevated PTH levels (7590 ng/l) until October 2004 when corrected calcium rose to 3.0 mmol/l with PTH 90.4 ng/l. CT neck showed an enhancing septated low density mass 12×10 mm size in the upper aspect of the left carotid sheath. Repeat sestamibi scan proved inconclusive. In October 2006 she was admitted with her third hypercalcaemic crisis with corrected calcium 4.25 mmol/l and PTH 200 ng/l. As before, she responded well to intravenous fluids and pamidronate therapy with calcium improving to 2.44 mmol/l. Further CT neck showed increase in size of the left carotid sheath mass to 14×10 mm. Neck exploration in May 2007 showed a small nodule of parathyroid tissue between the left common carotid artery and internal jugular vein. Postoperatively, she had a myocardial infarction associated with cardiogenic shock and she died in June 2007.