Ultrasound (US) is the essential primary imaging modality for preoperative staging of differentiated thyroid cancer. Although contrast-enhanced neck CT has been routinely used for the evaluation of general head and neck malignancy, routine use of contrast-enhanced CT is not recommended for the differentiated thyroid cancer by most international thyroid societies, and they recommend very conservative selective use of CT only for locally advanced thyroid cancers. This recommendation seems based on the fact that iodinated contrast media may interfere with radio-iodine treatment and the added value of CT has been little investigated. Although the safety issue of CT contrast media is still controversial, the effect of CT contrast media on radio-iodine treatment seems not clinically significant if there is more than 2 month interval between intravascular administration of iodinated contrast media and radio-iodine treatment. Although CT has been widely used for preoperative evaluation of differentiated thyroid cancers in Korea, the added value of CT for detection of metastatic nodes has been little investigated. Compared with US, CT has advantages of less operator dependency and capability of scanning the whole neck. This suggests that CT may have complementary roles for detection of possible missing diagnosis of metastatic nodes by US and for detection of metastatic nodes at retropharyngeal area and low central neck (level 7 and low level 6 in some cases) which are not accessible by US. Because CT features of metastatic lymph nodes are different from those of US, combination of US and CT may have a potential to increase the diagnostic sensitivity for detection of metastatic cervical nodes. Recent studies suggest that CT may have a helpful complementary role for the evaluation of cervical metastatic nodes in differentiated thyroid carcinoma. However, added diagnostic value of CT and indication for CT use should be further investigated in the preoperative staging of differentiated thyroid carcinomas.