PURPOSE: To evaluate the usefulness of gray scale and color Doppler US in the differentiation of endometrial lesions. MATERIALS & METHODS: Twenty eight women with endometrial lesions proved by surgery(n=17), dilatation & curettage(n=9), and follow-up ultrasound(n=2) were included in this study. Sonographic morphologic analysis included AP diameter, echotexture, central stripe, margin of endometrial lesions, and subendometrial halo. Analysis of Color Doppler US included pulsatility index(PI), resistance index(RI), peak systolic velocity(PSV). Histologic diagnoisi were endometrial carcinoma(n=5), endometrial hyperplasia(n=4), endometrial polyp(n=3), submucosal myoma(n=13), secretory endometrium(n=3). RESULTS: Different from benign endometrial lesions, endometrial carcinomas had irregular mass margin with partial interruption of subendometrial halo in all five cases. Central stripe noted in secretory phases(3/3), endometrial hyperplasia(2/4), and submucosal myoma(8/13), was either separated(n=1) or displaced(n=7) in submucosal myoma, but straight in others. Six of 13 submucosal myomas were hypoechoic, but others were iso or hyperechoic. Cystic change was noted in endometrial polyp(2/3), endometrial hyperplasia (2/4), submucosal myoma(1/13). Color signal was noted in 24 of 28 cases. PI and RI of endometrial cancer were 1.08 and 0.66, respectively, and higher than those of benign diseases. PSV of endometrial cancer was 0.16m/sec and lower than those of benign diseases. CONCLUSION: Subendometrial halo was useful in differentiation of endometrial carcinoma from other benign endometrial loseions. Echotexture, central stripe was useful in differentiation of each benign endometrial lesions. Color Doppler US was not heplful in differentiation of endometrial lesions.