OBJECTIVES: To describe the sonographic features of endometrial cancer in relation to stage, grade, and histological type using the International Endometrial Tumor Analysis (IETA) terminology. METHODS: Prospective multicenter study on 1714 women with endometrial cancer undergoing a standardized transvaginal grayscale and Doppler ultrasound examination by an experienced ultrasound examiner using a high-end ultrasound system. Clinical and sonographic data were entered into a web-based protocol. We assessed how strongly sonographic characteristics, according to IETA, were associated to outcome at hysterectomy, i.e. tumor stage, grade, and histological type. RESULTS: After excluding 176 women (no or delayed hysterectomy, final diagnosis other than endometrial cancer, or incomplete data), 1538 women were included in our statistical analysis. Median age was 65 years (range 27-98), and median BMI 28.4 (range 16-67), 1378 (89.7%) women were postmenopausal, and 1296 (84.2%) reported abnormal vaginal bleeding. Grayscale and color Doppler features varied according to grade and stage. High-risk tumors (stage 1A, grade 3 or non-endometrioid or ≥ stage 1B) were less likely to have regular endometrial myometrial border (difference of -23%, 95% CI -27 to -18%), whilst they were larger (mean endometrial thickness; difference of +9 mm, 95% CI +8 to +11 mm), more frequently had non-uniform echogenicity (difference of +10%, 95% CI +5 to +15%), a multiple, multifocal vessel pattern (difference of +21%, 95% CI +16 to +26%), and a moderate or high color score (difference of +22%, 95% CI +18 to +27%), than low-risk tumors. CONCLUSION: Grayscale and color Doppler ultrasound features are associated with grade and stage, and differ between high and low risk endometrial cancer.