Introduction: Information about the incidence and risk factors of venous thromboembolism (VTE) after thyroid operation is limited. This study aimed to analyze the incidence and risk factors of postoperative VTE in patients who had undergone thyroid surgery. Materials and methods: A prospective, multi-center cohort study was performed from June 2013 to June 2015 in 3 hospitals throughout South Central China. We analyzed 5029 patients who had undergone thyroid operation and received no VTE prophylaxis postoperatively. For the diagnosis of deep vein thrombosis (DVT), bilateral whole-leg ultrasound was conducted in patients with a high pretest probability of DVT. Lung ventilation/perfusion scintigraphy, pulmonary angiography, or helical computed tomography was implemented in patients suspected to have pulmonary embolism (PE). Results: DVT was diagnosed in 18 patients (0.36%). No patient was diagnosed with PE. Binomial logistic regression analysis revealed that age and left lower limb intraoperative venous access (IVA) were significant risk factors for DVT. The incidence of DVT increased as the number of risk factors increased. Conclusions: VTE is uncommon in patients who have undergone thyroid surgery. The left lower limb was not an appropriate insertion site IVA. Pharmacologic thromboprophylaxis was not mandatory, particularly in those patients without risk factors. (C) 2016 Elsevier Ltd. All rights reserved.