This study was undertaken to assess the effectiveness of using serum CA125 and vaginal examination as a screening test for ovarian cancer in apparently healthy females. Two thousand five hundred and fifty healthy females aged 40 and over were recruited to participate in a screening study involving a questionnaire, serum CA125 measurement and vaginal examination. Females with either an elevated CA125 level or abnormal vaginal examination had a pelvic ultrasound performed as a secondary procedure. The positive predictive values of an elevated serum CA125 level, and a combination of CA125 level measurement and vaginal examination for ovarian cancer, were 1/100 and 1/3, respectively. The specificities of serum CA125 levels, vaginal examination and both in combination were 96.1%, 98.5% and 99.9%, respectively. In postmenopausal females the positive predictive values were improved with CA125 measurement alone, giving a positive predictive value of 1/24. Seventeen females underwent operative procedure as a result of the screening-only one of these was for an ovarian cancer. The combination of serum CA125 measurement and vaginal examination is not an effective screening test in the general population, although in postmenopausal females it does achieve acceptable specificities and positive predictive values.