<p>Hypocalcemia is a common complication following total thyroidectomy, which may be transient or, in some cases, permanent, necessitating long-term calcium supplementation. This study aims to evaluate the relationship between preoperative vitamin D3 levels and postoperative hypocalcemia, excluding other confounding risk factors. This prospective analytical study was conducted at the Department of ENT of a tertiary referral center in Nepal, from March 2020 over a period of one and a half years. A convenient sampling method was used. All patients undergoing total thyroidectomy, with or without neck dissection, who met the inclusion criteria were enrolled. Patients with devascularized parathyroid during surgery, chronic kidney disease (CKD), or synchronous tumors (e.g., parathyroid adenoma with thyroid malignancy) were excluded. Based on preoperative vitamin D3 levels, patients were categorized into three groups: deficient (&lt; 20 ng/ml), insufficient (21–29 ng/ml), and sufficient (≥ 30 ng/ml). A total of 38 patients underwent total thyroidectomy, of whom 27 (71%) were female. Vitamin D3 deficiency was noted in 16 (42%) patients. Preoperative vitamin D3 levels and categories were compared with postoperative parameters including day 1 intact parathyroid hormone (iPTH), serum calcium on postoperative days two and five, and third month iPTH levels. No statistically significant correlations were found. Additionally, there was no significant association between preoperative vitamin D3 status and the occurrence of symptomatic hypocalcemia requiring supplementation at discharge or at three months postoperatively. Preoperative vitamin D3 status did not significantly correlate with postoperative iPTH or calcium levels, either during the hospital stay or at three months following total thyroidectomy. Similarly, the requirement for calcium supplementation post-surgery was not significantly associated with preoperative vitamin D3 levels.</p>