Objectives: The aim of this study is to determine the risk of neoplasm and malignancy in thyroid fine needle aspiration (FNA) diagnosed as atypia of undetermined significance with Hürthle cell change (AUS-H) or Hürthle cell neoplasm (HCN). Study Design: A computerized search of our laboratory information system was performed to identify all thyroid FNA and correlating surgical pathology diagnoses including Hürthle cell or oncocyte in the diagnostic nomenclature. The risks of neoplasm and malignancy were calculated for AUS-H and HCN categories separately. Results: For the 29 AUS-H cases, the follow-up histology demonstrated 15 benign lesions, 4 follicular adenomas, 7 Hürthle cell adenomas, 1 papillary microcarcinoma (PMC), 1 follicular carcinoma and 1 Hürthle cell carcinoma. For the 93 HCN cases, the follow-up histology demonstrated 28 benign lesions, 9 follicular adenomas, 32 Hürthle cell adenomas, 2 PMCs, 2 papillary thyroid carcinomas, 6 follicular carcinomas and 14 Hürthle cell carcinomas. Conclusions: The risks of neoplasm and malignancy were 62 and 7% for the AUS-H category and 73 and 24% for the HCN category, respectively. The risk of malignancy for the AUS-H patients is within the 5- to 15-percent range suggested by the Bethesda System for Reporting Thyroid Cytology and within the 15- to 30-percent range suggested for follicular neoplasms.