Although over 25 prospective screening studies for ovarian cancer have been published, none have been able to demonstrate conclusively a reduction in mortality from ovarian cancer in the screened group, for either the general or the high-risk population. Jacobs et al. recently reported the findings of the first randomized controlled trial of ovarian cancer screening[11]. Postmenopausal women aged 45 years or older were randomized to a control group (n = 10 977) or to a screened group (n = 10 958). The screened group underwent annual multimodal screening for 3 years. All women were followed up to see whether they developed invasive epithelial ovarian cancer. Compliance was excellent and the positive predictive value of a positive screen was high at 21%. Although the study was too small to assess impact on mortality, median survival (72.9 months) was significantly higher in women with ovarian cancer in the screened group than in those in the control group (41.8 months). Other recently reported transvaginal ultrasound trials from Kentucky[9] and from Japan[12] have also recently reported encouraging results. The Kentucky trial showed a 5-year survival of 83.6 ± 10.8% in the screened group, and the Japanese trial found there was an increase in the percentage of stage I tumours diagnosed and treated in the department from 29.7% to 58.8% after the trial was initiated. These results need to be interpreted with caution due to the lack of control groups, but all emphasize the need for a randomized control trial. This needs to, in addition to establishing the impact of screening on ovarian cancer mortality, comprehensively tackle the issues of target population, compliance, health economics and physical and psychological morbidity of screening. Such a trial has now been initiated, the UK Collaborative Trial of Ovarian Cancer Screening (UKCTOCS), funded by the Medical Research Council, the Cancer Research Campaign, the Imperial Cancer Research Fund and NHS Research and Development and co-ordinated by the Gynaecology Cancer Research Unit at St Bartholomew’s Hospital, London. The three-armed randomized control trial aims to recruit 200 000 post-menopausal women, aged 50–74 years, randomized in a 1:1:2 ratio to ultrasound screening, multimodal screening using the Risk of Ovarian Cancer algorithm and a control group who will not be screened. Participants will be invited from regional age/sex registers, overcoming the inherent flaws of self-referral. Screening will occur in 12 collaborating gynaecological oncology centres in the UK and participants randomized to screening will undergo six screens at annual intervals. All participants will be followed up by postal questionnaire and via the cancer registry. The primary end-point of the study is ovarian cancer mortality 7 years after randomization. Additional end-points include quality of life, health economics, morbidity and compliance with screening. The performance of the two screening strategies will also be compared. The results of this trial will form the basis for making an informed decision about the implementation of general population screening for ovarian cancer. The adoption of annual screening as standard practice in the high-risk population makes it impossible to institute a randomized control trial with a control group who are not screened in this group. However, in order to develop an optimal screening strategy in the high-risk population, a multicentre National Familial Ovarian Cancer Screening Study (UK-FOCSS) involving 5000 women is being set up in the UK. A similar trial is underway in the USA.