Objectives. To determine the prevalence of incidentalomas in a patient population with no known thyroid malignancy who underwent whole body FDG-PET/CT for staging or restaging of neoplasia. The additional aim of the study was to evaluate the feasibility of using PETCT as a screening tool for malignant thyroid incidentalomas. Methods. Retrospective review of medical records of all the thyroid exams done at our institution between January 1, 2000 and August 20, 2008. We made a criterion of PET/CT as the primary method of detection of incidentalomas. Results. From a total of 8464 thyroid exams, 156 incidentalomas were found and 40 incidentalomas underwent anatomopathology analysis, which was used as gold standard. Chi-square analysis was used to analyze the data. There is no significant association between SUV value and the prevalence of incidentalomas. Discussion. From January 1, 2000 to August 20, 2008, incidentalomas have a prevalence of 1.84% at our institution. 38% of the incidentalomas that were biopsied were characterized as representing malignant tumors. Conclusion. Focal, abnormal FDG uptake representing incidentalomas must be followed up with biopsies. It is impractical to use PET/CT as a screening tool to detect incidentalomas for the general population but it must be done in patients with history of any type of cancer.