Background: Uterine myomas may resemble uterine sarcomas in some cases. However, the rate of benign myomas appearing as sarcomas at an ultrasound examination is not known. The objective of this study is to determine the percentage of benign myomas that appear suspicious for uterine sarcoma on ultrasound examination. This is a prospective observational multicenter study (June 2019-December 2021) comprising a consecutive series of patients with histologically proven uterine myoma after hysterectomy or myomectomy who underwent transvaginal and/or transabdominal ultrasound prior to surgery. All ultrasound examinations were performed by expert examiners. MUSA criteria were used to describe the lesions (1). Suspicion of sarcoma was established when three or more sonographic features, described by Ludovisi et al. as frequently seen in uterine sarcoma, were present (2). These features are no visible myometrium, irregular cystic areas, non-uniform echogenicity, irregular contour, cooked appearance, and a Doppler color score of 3-4. In addition, the examiners had to classify the lesion as suspicious based on her/his impression, independent of the number of features present. Eight hundred and ten women were included. The median maximum diameter of the myomas was 58.7 mm (range: 10.0-263.0 mm). Three hundred and forty-nine (43.1%) of the patients had more than one myoma. Using the criterion of >3 suspicious features, 40 (4.9%) of the myomas had suspicious appearance. By subjective impression, the examiners considered 40 (4.9%) cases suspicious. The cases were not exactly the same. We conclude that approximately 5% of benign uterine myomas may exhibit sonographic suspicion of sarcoma. Although it is a small percentage, it is not negligible.