Background: Declines in serum calcium or intact parathyroid hormone (iPTH) levels after surgery have been suggested as being reliable predictors of postoperative hypocalcemia. Although measurements of serum calcium or iPTH allow the identification of patients who have no risk of hypocalcemia after total thyroidectomy, it is not always easy to predict which patients can be discharged early from the hospital or to identify those requiring close monitoring of serum calcium levels or those that should receive calcium and vitamin D supplements. Aim of the work To evaluate early postoperative parathyroid insufficiency following total thyroidectomy by estimating parathyroid hormone and calcium level in the early postoperative period, and whether we can rely on to start Ca supplement or not. Patients and methods: This study was done in General Surgery department, Zagazig University on 50 patients; 10 males (20%)) 40 females (80%) who underwent total thyroidectomy. Serum total Calcium and Parathormone levels were evaluated in all patients 6 h and 24 h in early postoperative period. Results: Our results showed highly significant VALUE OF relative decline of serum calcium and parathyroid hormone 6 h and 24 h after total thyroidectomy. The results showed also highly significant positive correlation between serum calcium and parathyroid hormone both preoperative and postoperative and highly significant positive correlation between relative decline in serum calcium and relative decline of serum parathyroid hormone at both 6h and 24 h after total thyroidectomy IN HYPO CALCEMIC PATIENTS. There was no significant relationship between hypocalcemia and any of demographic, clinical, ultrasonographic and pathological data. There is significant relationship between both relative decline of serum calcium and relative decline parathyroid hormone and postoperative hypocalcemia. Conclusion: Relative decline of parathyroid hormone 6 h and 24 h after total thyroidecomy is a good predictor of postoperative hypocalcemia and is reliable for allowing safety discharge of patients 24 h after total thyroidectomy.