Introduction Hypocalcaemia after thyroidectomy is observed with increasing frequency, often resulting in prolonged hospital stay with increased use of resources, delayed return to work and reduced quality of life. The administration of vitamin D is essential in the therapy of postoperative hypocalcaemia. What has not been examined so far is whether and how routine preoperative vitamin D prophylaxis can help to prevent postoperative hypocalcaemia. Materials and methods This is a prospective cohort study which was conducted from June 2016 to July 2017 at a tertiary care hospital. One hundred and two patients with thyroid disease who were admitted for thyroid surgery were interviewed and underwent physical examination and laboratory investigations. The patients enrolled in the study were randomly assigned to either the Interventional group (Pre-operative Vitamin D Supplementation) or the control group (placebo). The work is reported in line with the standards set by STROCCS criteria [1]. Results Out of 102 patients there were 89 females (87.25%) and 13 males (12.7%) with a mean age of 39.35 ± 7.01 years. In the test group 45 (88.2%) patients had no clinical hypocalcemia, 5 (9.82%) had latent while 1 (2%) patient had overt hypocalcemic symptoms. In placebo group 37 (72.5%) had no clinical hypocalcemia, 10 (19.6%) had latent and 4 (7.8%) had overt hypocalcemic symptoms. (P-value Conclusion As the general population is deficient in Vitamin D, a prophylactic vitamin D dose given in immediate preoperative period can significantly reduce acute symptomatic postoperative hypocalcemia in patients undergoing thyroid surgery.