Thyroid ultrasound revealed a 14x14x22 mm nodule with a mixed echo pattern, rough calcification foci and cystic-necrotic areas in the left lobe lower pole. Fine needle aspiration biopsy of this nodule complied with benign follicular nodule. Bone scintigraphy is usually performed to evaluate a wide variety of skeletal abnormalities (1). Tc-99m-labeled diphosphonates have been used for bone scanning as a major diagnostic tool since the beginning of 1970s (2). Tc-99m MDP has rapid blood clearance, excellent in vivo chemical stability, and a high bone-to-soft tissue ratio, thus, it is ideal for bone imaging (3). In the literature, many cases of incidental Tc-99m-MDP uptake by the soft tissue have been reported due to various reasons, both benign (tumoral calcinosis, myositis ossificans) and malignant (sarcomas, adenocarcinomas, metastases) conditions (4,5). Mechanisms leading to increased extraosseous Tc-99m MDP uptake include extracellular fluid expansion, enhanced local vascularity and permeability, and high tissue calcium concentration. The composition of the calcium deposition and the presence of other elements (e.g. iron and magnesium) are important (4). It is known that there may be incidental Tc-99m MDP uptake in the thyroid gland, in calcific thyroid nodules, secondary to biopsy interventions, anaplastic thyroid carcinoma or metastatic thyroid cancer (4,6). In our case, unexpected incidental Tc-99m MDP involvement was presented in a functionally active thyroid nodule. This appearance of Tc-99m MDP uptake in an active thyroid nodule, first demonstrated in this case, is thought to be secondary to the presence of microcalcifications in the nodule