Purpose: Sono-guided FNAC (fine needle aspiration cytology)is a safe and accurate diagnostic procedure for thyroid nodules. We examined the use of an extension tube in FNAC as useful. Methods: We reviewed 175 cases of patients with thyroid nodules where an extension tube was used in sono-guide FNAC and 153 cases where a syringe holder was used in Jeonju Jesus hospital, from July 2005 to September 2006. Results: For cases with an extension tube, tumor size was smaller than 1 cm (38%), from 1 cm to 2 cm (27%), or larger than 2 cm (35%), with cytology results of benign (73%), intermediate (8%), malignant (7%), or nondiagnostic (12%). In cases with a syringe holder, tumor size was smaller than 1 cm (40%), from 1 cm to 2 cm (40%), or larger than 2 cm (20%), with cytology results of benign (51%), intermediate (4%), malignant (3%), or nondiagnostic (42%). The nondiagnostic percentage in cases where an extension tube was used was lower than in cases using a syringe holder. However, the number of tumors larger than 2 cm was significantly larger in the syringe group than the extension tube group.