BACKGROUND The cribriform-morular variant of papillary thyroid carcinoma (cmvPTC) is rare. There are few if any studies of the ultrasonographic (US) features of cmvPTC. The aim of this study was to determine the characteristic US and clinical features of the cmvPTC. METHODS A retrospective review of the US and clinical features was performed on 18 surgically confirmed cmvPTCs in five patients who were seen at our institution between January 2000 and December 2010. RESULTS All patients were female with a mean age of 28 years (range, 19-46 years). Two patients presented with palpable lesions, and the other patients were incidentally detected during screening US. On US, the majority of nodules had well-defined, oval to round shapes, and were hypoechoic and solid without calcifications. However, 6 (33.3%) of 18 nodules did have a cystic change. The size of the lesions varied from 0.3 to 3.0 cm (mean, 1.11 cm). None of the nodules were diagnosed as malignant based on the US criteria, but all except one patient had a cytology of their thyroid nodules that was read as malignant, without revealing the subtype of their PTC. Two of the five patients had familial adenomatous polyposis (FAP), and they had bilateral multiple nodules. No metastatic lymph nodes or extrathyroidal extension were identified. To date, none of the patients has had recurrence or metastasis during their mean follow-up of 25 months after thyroidectomy. CONCLUSIONS It appears that most cases of cmvPTC do not have features of malignancy on US and that they are indolent tumors as far as their clinical and histological features are concerned.