The Optimam Mammography Image Database (OMI-DB) has been created to support research involving medical imaging with the aim of optimising the use of existing and adoption of new X-ray imaging technologies, including digital breast tomosynthesis (DBT), for detecting breast cancers and improving early detection in the NHS Screening Programme. A centralised flexible image repository which prospectively collects images and associated data from multiple sites throughout the UK. It contains both processed and unprocessed mammograms, typically for women who have had a screen detected breast cancer and contain two views of each breast (MLO and CC).