Transvaginal ultrasound scanning with colour Doppler imaging can be used to detect early ovarian cancer. About one in three women with a family history of the disease and a positive screening result (i.e. a persistent intraovarian mass with a characteristic blood supply) will have histological signs of primary cancer. A randomized controlled clinical trial should be undertaken to assess whether screening and immediate treatment of women from the general population will improve survival rates from the disease.