Primary role of ultrasound in patients with thyroid nodule is no determine the multiplicity and detect occult carcinoma. We analyzed US findings of 53 thyroid carcinomas with multiple nodular lesions from January 1988 to December 1991. The results were as follows : 1. 109 malignant nodules in 53 cases and 24 benign in 23 were comfirmed. 2. The nature of the masses were solid in 72 malignant nodules (74.2%), and complex in 25 (25.8%) of which 19 were predominantly solid. 3. The echo pattern of the solid and solid predominant masses were hypoechoic in 78 malignant nodules (80.4%), hyperechoic in 10 (10.3%), and isoechoic in 3 (9.3%). 4. Internal punctate calcifications within the masses were observed in 31 malignant nodules (31.9%). 5. Halo sign was present in 16 malignant nodules (16.5%). 6. The preoperative sonographic diagnosis of thyroid carcinoma was made in 39.4% of 53 cases with multiple nodules on US. In conclusion, the number, and halo formation of nodules were insignif cant to differentiate the benign nodule from the malignant. The heterogeneous hypoechoic nodules with size greater than 4cm, multiple stippled calcifications, displacement of the trachea or other surrounding structures of combined lymph node enlargements seem to indicate the possibility of malignancy.