Background: Thyroidectomy is one of the most common surgical procedures in the world. After thyroidectomy postoperative nausea and vomiting (PONV), and so pain is high. Voice dysfunction can also occur. Aim: The aim of this study is to assess the effects of a preoperative single dose of Dexamethasone on postoperative nausea, vomiting, pain and vocal dysfunction in patients undergoing total thyroidectomy. Patients and methods: A prospective randomized comparative study was done from September 2014 to February 2016 in Ain shams university hospital (a tertiary care hospital) , general surgery department (endocrine surgery unit), Cairo, Egypt. The study included one hundred patients suffering from thyroid diseases for which total thyroidectomy was indicated. Patients were divided into two groups: Group A: received preoperative prophylactic dexamethasone. Group B: didn't receive preoperative prophylactic dose of dexamethasone. Preoperative workup included History taking, Examination; general and local, preoperative investigations including laboratory and radiological. ECG, Echocardiography and pulmonary function tests when indicated. Vocal cord and voice function evaluation (1. direct laryngoscopy, 2. Voice Recording, 3. Aerodynamics (F0, Jitter and Shimmer). Patients were put into 2 treatment groups; group1 received 8 mg/2 mL of Dexamethasone and the control group 2 received 2 mL NaCl 0.9% each in 100 mL of physiologic saline given intravenously (I.V.). Post-Operatively, patients were assessed for nausea, vomiting, pain and voice changes done together with search for any postoperative complications. This was done postoperatively and at regular visits conducted at 2 weeks, 1, 2, 4 and 6 months. Results: The study included 100 patients. Group (A) included 47 patients and group (B) included 53 patients. There was no statistically significant difference between both groups as regards age, sex, Baseline voice recording (preoperative voice recordings), while post-operative voice recording showed significant changes in results of dysphonia with P value 0.025 in dexamethasone group (post-operative improvement), although other voice recording parameters showed no significant changes compared to preoperative levels. Pre-operative (base line) aerodynamics showed no significant difference between the two groups and so postoperative analysis of aerodynamics which showed close results as regard fundamental frequency and Jitter except for the Shimmer values which showed statistically significantly different values between the two groups. Post-operative dyspepsia study showed that 12.5 % of patients who didn’t receive dexamethasone experienced various degrees of dyspepsia while no patients from the other group suffered from dyspepsia, however the results were not statistically significant. Postoperative pain showed a highly significant difference between the dexamethasone group and the other group where Group (A) patients showed lower values of average pain. Conclusion: A preoperative single dose of dexamethasone can significantly reduce nausea, vomiting, and pain, and improve postoperative voice function so that this strategy can be routinely applied in thyroidectomy operations. Key words: thyroidectomy, nausea, vomiting and voice dysfunction.