Comparative study with ovarian tumors between ultrasonic and histological diagnoses was performed on 64 patients who had all undergone laparotomy, and diagnosed histologically at Shimane Medical University Hospital from October '79 to September '83. The ultrasonically correct diagnostic rate of ovarian tumors was 80.0% (52 out of 65 cases). With ultrasonic diagnosis of malignant ovarian tumors, the false positive rate was 22.2% (4 out of 18 cases), and the false negative rate nil (0 out of 47 cases). Therefore, for helping to decide between benign and malignant, ultrasonography should be a pertinent diagnostic tool in the primary screening of ovarian tumors.