Background: Post-thyroidectomy hypoparathyroidism is a common complication of thyroid surgery, characterized by low Parathyroid hormone  (PTH) levels, which increases treatment costs and hospital stays.
Objectives: This study aimed to compare the effects of truncal and branch ligation of inferior thyroid arteries (ITA) near the thyroid capsule on serum calcium and PTH levels after surgery.
Patients and methods: This was a prospective clinical randomization trial conducted on 100 multi-nodular goiter patients underwent thyroidectomy, 34 were males and 66 were females.  The assessments of PTH and Ca. levels were done on the 1^st, 3^rd day & 30^th days post-thyroidectomy.  
Results:  There was no significant difference between the two groups Regarding age, sex, residence. The main trunk ITA ligation group showed a significant increase in the need for replacement with calcium and vitamin D, as well as a decrease in Ca and PTH at the first and second assessments compared to pre-operative results. However, there was no significant difference between the pre-operative and third assessments regarding Ca level and PTH. The selective branch ITA ligation group showed a significant decrease in PTH at the second assessment but insignificant decrease in Ca level.
Conclusion:  Ligation of the inferior thyroid artery (ITA) reduces the likelihood of postoperative hypocalcemia compared to trunk ligation. However, it was limited to the immediate postoperative period, as outcomes were similar in subsequent days.