Confirmation and clarification of an adnexal mass is a domain of transvaginal ultrasound. The highest hit ratio is achieved by experienced sonographers relying on a dedicated set of sonomorphologic criteria. Less experienced may consult validated scores, colour doppler findings and the tumor marker CA125. The assignment to one of the three groups simple cyst, benign tumor, malign tumor should lead to an adequate procedure (control, laparoscopy, laparotomy). Whenever possible to avoid unnecessary surgical interventions, simple cysts should be treated conservatively. Also in postmenopausal woman 50% of them resolve spontaneously in 60 days. Ovarian cancer screening is still an unsolved problem. Nearly all established methods fail because of the low prevalence of ovarian cancer at around 0.4%.