Establishment of mammography screening in Sweden has progressed logically from pilot study through clinical trials to service screening. Screening with mammography for early detection of breast cancer has been provided by all Sweden's 26 county councils since 1997. It took 23 years from the initial pilot study through clinical trials to the establishment of mammography service screening throughout Sweden. In the screening rounds completed by 1995-96, and provided by all but one county council, 1040000 women participated, corresponding to 81% of those invited. The national average recall rate was 2.2%, and consequently 23000 women were recalled for additional investigations. Eleven county councils invited women aged 40-74, six invited women aged 50-69, the remaining eight invited women between both these age intervals. Mammography outside screening programmes-clinical mammography-is available throughout Sweden. About 100000 women a year were referred for clinical mammography and about 50% of these were either younger or older than those invited for screening. A negative relation between the use of clinical mammography and participation in the screening programmes was noticed.