This chapter offers an overview of the epidemiology and aetiology, clinical and histological characteristics and classification, and staging of thyroid and parathyroid neoplasms before providing a more focused and illustrated description of the imaging findings. The indications and the role of ultrasound, ultrasound-guided fine needle aspiration, cross-sectional modalities and 18F-FDG-PET in the diagnosis and follow-up of thyroid cancer are discussed, with reference to the particular imaging characteristics of different tumour types. The embryology of parathyroid gland development is addressed and the relative advantages of ultrasound, scintigraphy, cross-sectional modalities and percutaneous venous sampling in the management of hyperparathyroidism are described.