Background In 1989 BreastScreen SA started screening for breast cancer in South Australia. Methods The programme concentrated on women between the ages of 50 and 69, using a 24-month screening interval and a joint method of mammography, clinical examination and self-detection. Results This paper is a summary of our efforts to provide an assessment of the impact of the screening programme in terms of additional survival time past the age of first detection of the disease. Discussion The concept of benchmarks is introduced, and the survival advantages for screened women is measured from these benchmarks. Conclusion The women in the BreastScreen SA service, who had primary breast tumours, had an estimated additional survival advantage of 2.6 years. Some statistical modelling allowed us to extrapolate to other screening designs.