Background and Objectives: Fine needle aspiration (FNA) cytology is a simple, safe and relatively accurate procedure of diagnosing thyroid nodules. Although the frozen section biopsy is well known as more reliable method than FNA and has high specificity, whether it is necessary it leaves room for adverse criticism. Authors have compared preoperative FNA cytology and frozen section biopsy with permanent histologic findings and evaluated the significance of FNA cytology and frozen section biopsy. Materials and Methods: The medical records of 110 patiens who underwent FNA cytology and frozen section during thyroidectomy from September. 1997 to December. 2001 at the Department of Otolaryngology, School of Medicine, Keimyung University were analyzed retrospectively. Results: Sensitivity, specificity, accuracy of FNA was 75%, 91.4%, and 85.5% respcetively. Sensitivity, specificity and accuracy rate of frozen section biopsy were 92.5%, 100% and 97.3% respectively. Conclusion: FNA is simple, with rare complication and its diagnostic accuracy is comparatively so high that it is being used as primary test to diagnosis thyroid nodules. But frozen section is more accurate and may be helpful to suspicious FNA findings or if it beyond capacity of FNA. Therefore despite of the fact that the intra-operative frozen is more expensive and time consuming, it is very helpful to the treatment of thyroid nodules by using jointly with FNA.