The sonographic findings of histologically proven 160 cystic masses of ovary were analized to find helpful diagnostic sign. The results were as follows: 1. The bilateralities were identified in 1 serous cystadenocarcinoma(33%) 2 mucinous cystad-enocarcinoma(40%) & 2 dermoid cysts(5%) 2. 76% of serous cystadenoma were homogenous cystic masses. 3. 64% of mucinous cystadenoma were cystic masses with internal septation(7 daughter cysts), & 5 mucinous cystadenomas were showed mltiple homogenous low level echoes within it. 4. 64% of dermoid cyst revealed strong echogenic solid component within the upper part of the cyst. 5. 80% oc corpus luteal cyst were mainly cystic lesion with several low-level internal echoes. 6. 805 of malignant ovarian mass revealed irregular thick internal septation& irrgular inhomogenous internal solid components within it.