The malignancy diagnostic values of each ultrasound signs were: poor Echos: benign 29.6%, malignant 76.1% (2=41.96, p =0.001) irregular limit: benign 10.2%, malignant 37.5% (2 =20.78, p =0.001) intranodular calcification: benign 16.7%, malignant 47.7% (2 =22.02, p =0.001) neck lymphatic nodule: benign 11.1%, malignant 39.8% (2 =21.85, p = 0.001) Conclusion: the sensitivity and the selectivity of thyroid ultrasound in prediction of multinodular goiter malignancy were 46.6% and 87% respectively.