We report a case of thyroid incidentaloma detected by 18F-choline PET/CT. A 66-year-old male patient with a history of prostate cancer underwent a 18F-choline PET/CT for restaging. PET/CT revealed a focal area of increased 18F-choline uptake corresponding to a hypodense nodule in the right lobe of the thyroid. Based on PET/CT findings, the patient underwent a ultrasonography guided fine-needle aspiration biopsy which demonstrated the presence of a benign thyroid nodule.