Postoperative hypocalcaemia is the most frequent and common complication after total thyroidectomy. It is necessary to diagnose or to predict hypocalcaemia immediately after total thyroidectomy for minimizing complications. A prospective observational study was carried out in the Department of Clinical Pathology in collaboration with Department of Microbiology & Immunology, Department of Surgery, Department of Otolaryngology, Bangabandhu Sheikh Mujib Medical University (BSMMU) and Department of Otolaryngology, Dhaka Medical College & Hospital (DMC&H), Dhaka, during the period of September 2010 to August 2011 to evaluate intraoperative (20 minutes after total thyroidectomy) parathyroid hormone (PTH) measurement as a predictor of post thyroidectomy hypocalcaemia.