Aim: To find out the incidence rate of post-thyroidectomy immediate hypocalcemia within 48 hours and explore the association of pre-operative vitamin D and parathyroid hormone (PTH) levels.Methods: This retrospective study was conducted among 122 patients who underwent total thyroidectomy over one year (from January 2018 to December 2018) in Prince Sultan Military Medical City, Riyadh, Saudi Arabia. After thyroidectomy, all patients were admitted and observed for at least 24-48 hours. The postoperative hypocalcemia, alkaline phosphatase (ALP), phosphate (PO4), parathyroid hormone (PTH), and vitamin D level were collected.Results: During 2018 a total of 122 (mean age 41.6±1.2 years; females 90.2%) patients underwent total thyroidectomy. The mean calcium level in the first two days was 2.07 mmol/L and 2.01 mmol/L. Most of the cases of hypocalcemia occurred on day 1 postoperatively. Hypocalcemia mainly occurs in patients with benign pathology. The level of vitamin D in those patients with benign pathology was significantly lower as compared to those with malignant pathology (49±23 vs 62±25; P=0.009). The overall mean level of vitamin D was 54.6±25 (50-150 nmol/L). Interestingly, there were no correlation between pre-operative vitamin D, PTH level and postoperative hypocalcemia. There were no statistically significant differences between postoperative hypocalcemia with other parameters except for pre-operative alkaline phosphatase which was barely positive (P=0.052).Conclusion: The outcomes of this study manifestly illustrated that a significant decline in calcium level after the surgery. In contrast to previous studies, our findings did not show a significant correlation between vitamin D level and hypocalcemia. This could be due to small sample size. Furthermore, the mean level of vitamin D in our cohort was 54 which was within the normal range. Further, well-designed randomized controlled trials with greater sample sizes are necessary to validate our findings.