Introduction: Thyroid cancer is the most common endocrine malignancy worldwide with better outcome if timely and properly managed. Surgery followed by radioactive iodine (RAI) ablation remains the mainstay in the management of differentiated thyroid cancer (DTC). In Tanzania however, few patients with DTC receive RAI ablation post-surgery, and most of these present late, with advanced disease resulting in poor treatment outcome. The objective of this study was to determine the cause for late referral by assessing clinician’s awareness and knowledge on the management of DTC and the use of RAI in Tanzania. Methods: This descriptive cross sectional study was carried out in referral hospitals in Tanzania. Data collection used a standardized self-administered questionnaire. Information sought included awareness, knowledge and practices of clinicians on the management and the use of RAI on patients with DTC was explored. Results: Majority of clinicians managing DTC patients were males (86%), in-training surgeons (54%), and attended less than ten DTC patients per year (62%). About 44% of in-training surgeons never heard of nuclear medicine (p=0.04), and 20% were not aware of the role of RAI in the management of DTC (p=0.031). Only 7.3% of surgeons were aware of the role of thyroxine therapy, or RAI ablation post-surgery. Of all DTC patients managed surgically, only 16% had total thyroidectomy with lymphadenectomy (p=0.05). Conclusion: The findings of this study indicate there is insufficient knowledge on proper management and use of RAI on patients with DTC among clinicians in Tanzania.