Positron emission tomography (PET) and PET/computed tomography (PET/CT) with different tracers are imaging methods increasingly used in patients with thyroid and adrenal diseases. The aim of this article is to provide an overview based on literature data about the usefulness of PET imaging in this setting. PET and PET/CT with different tracers have been used in patients with thyroid diseases including differentiated thyroid carcinoma, medullary thyroid carcinoma, and poorly differentiated and anaplastic thyroid carcinoma. The usefulness of 18F-FDG-PET and PET/CT in assessing indeterminate thyroid nodules at fine needle aspiration biopsy and the clinical relevance of thyroid incidental 18F-FDG uptake has also been evaluated. Currently, great interest is being shown in a variety of PET tracers that target specific characteristics of adrenal gland function, allowing a more accurate characterization of adrenal masses and staging of adrenal tumors. Since PET/CT using different tracers is an expensive diagnostic tool which necessitates ionizing radiation exposure, cost-effectiveness studies are needed in order to define the appropriate use of this diagnostic method in various endocrine disorders.