When ovarian cancer is detected at an early stage, prognosis is good, which has led to discussion of a screening programme. The aim of this study was to identify and examine women at high risk of familial ovarian cancer, and to evaluate the inclusion criteria and the diagnostic methods for early detection of ovarian cancer. We report the first round screening findings in a prospective study of 180 women (mean age 43.4 years) considered to be at high risk of ovarian cancer based on family history. They were subjected to gynaecological examination with transvaginal ultrasound (TVU), CA125 and breast examination. Of these, 13 women with oestrogen receptor positive breast cancer had therapeutic oophorectomy and the ovaries were histologically examined. Among 180 women examined, nine ovarian cancers (among them two found at oophorectomy because of breast cancer) (mean age 49.0 years), seven benign tumours of the ovary (mean age 48.1 years), one cancer of the cervix, and four breast cancers were diagnosed. The prevalence of ovarian cancers (5%) was significantly more than in any previous series. TVU as a diagnostic method proved useful and detected 7/9 cancers, whereas CA125 was elevated in 4/9 cancers. To our knowledge, this is the first programme which has successfully delineated a high risk group and prospectively demonstrated their high prevalence of ovarian cancer. Possible biases are discussed.