Background: more than a century ago, thyroid surgery was a somewhat frightening operation, with a reported mortality rate of 40%. Nowadays, thyroidectomy is one of the most commonly performed surgical procedures. Hypocalcaemia is well recognized phenomenon following thyroidectomy; it has been a matter of interest in the past 100 years. Objective: to compare the effect of ligation of inferior thyroid artery main trunk versus its individual branches on postoperative hypocalcaemia. Patients and Methods: thirty patients with indication for thyroidectomy were randomly allocated into two groups; 15 patients each. Group A (15 patients) where the main trunk of inferior thyroid artery was ligated, while in group B (15 patients) the individual branches were ligated. Results: the results of this work showed that the incidence of post thyroidectomy hypocalcaemia, although was statistically significant in some comparisons of calcium and PTH, yet most of the levels were within the normal range, either pre or postoperatively with no clinical effects. Conclusion: ligation of the main trunk of inferior thyroid artery, although have a statistical significant on the parathyroid function and hypocalcaemia postoperatively, good surgical technique to identify and preserve the parathyroids, is the most important factor which may affect the postoperative hypocalcaemia.