Thyroidectomy is associated with one or more risk factors and postoperative complications like hoarseness, hypocalcemia etc. The objective of this study was to perform an analysis of risk factors and outcomes of postoperative complications of thyroidectomy. This study was conducted between the period of January 2020 to March 2021 in Al Jumhory Teaching Hospital at the City of Mosul-Iraq. Patients with abnormal preoperative blood Parathyroid hormone (PTH), Parathyroid adenoma, and low Calcium levels were excluded from the study. The study included 291 patients who were undergone thyroidectomy due to benign or malignant thyrotoxicosis. Patients were investigated for physical examination, thyroid ultrasonography, imaging, and fine-needle aspiration biopsies during the preoperative period. Hypocalcemia was compared with the previous thyroidectomy. Data were analysed through Statistical Package for Social Sciences (SPSS) version 25. A p-value less than 0.05 was considered significant in all statistical evaluations. A total of 236 (81%) female, and 55 (18.7%) were male patients in the study with the mean age of 45.02±13.5 years. When examined in terms of preoperative thyroid functions, 182 (62.7%) of the patients were euthyroid, while hyperthyroidism was the most common dysfunction in the 109 (34.4%) patients of the study groups. According to the clinic pathological diagnoses, Non-neoplastic Lesions (NNL) is the most common benign thyroid disease with a rate of (59%) and malignancy (41%). According to the findings of this study, the preoperative diagnosis of toxic hyperthyroidism and the PTH being close to the upper limit in the preoperative period were the major factors responsible for hypocalcemia and other complications.