Abstract Background: Post-operative hypocalcaemia is one of the most serious complications of total thyroidectomy with variable degrees of morbidity. Aim of Study: The aim of this study was to to compare the incidenceandto examine several preoperative and imme-diate post-operative factorsfor development of hypocalcaemia after total thyroidectomy in patients who underwent total thyroidectomy in Ain-Shams University and Damanhour Medical National Institute. Patients and Methods: This retrospective study was conducted in Ain-Shams University Hospital and Damanhour Medical National Institute in the period between December 2015 and December 2019. It included 62 patients who under-went total thyroidectomy. The data was collected from patients' files in the Record Department. Results: There were 52 female and 10 male patients. The mean age was 38 years. Multi-nodular goiter was the most common indication of total thyroidectomy. The mean pre-operative serum Ca was 8.1mg/dl in group A and 8.3mg/dl in group B. 3 (9.7%) patients in group A and 7 (22.5%) in group B developed post-operative hypocalcemia. The highest fre-quency of transient hypocalcaemia was on 2nd post-operative day in group A and on 0 day in group B. There was only one patient 3.2% who required calcium and vitamin D supplement for more than six months. Conclusion: Hypocalcaemia is one of the major concerns following total thyroidectomy that can be prevented by me-ticulous surgical technique, identification and preservation of parathyroid glands and its vascularity. Post-operative monitoring of serum calcium & early treatment can prevent significant morbidity.