Routine programme data and specially designed surveys from 3 demonstration sites were analysed to determine the implications of extending the NHS Breast Screening Programme (NHSBSP), to include routine invitations for women up to 69 years. All women aged 65–69 and registered with GPs in these areas received routine invitations for breast screening along with those aged 50–64. Overall uptake was 71% in women aged 65–69 compared with 78% in younger women, but was ≥ 90% in both groups who had previously attended within 5 years. Recall rates were lower for older women, but with a higher positive predictive value for cancer. The percentages of invasive cancer in different prognostic categories were similar in the 2 age groups. Older women took no longer to screen than younger women. The costs per woman invited or per woman screened were also similar to those for women aged 50–64, whilst the cost per cancer detected was some 34% lower in older women. Breast screening is as cost effective for women aged 65–69 as for those aged 50–64, with a higher cancer detection rate balancing shorter life expectancy. The proposed extension to the national programme will have considerable workforce implications for the NHSBSP and require additional resources. © 2001 Cancer Research Campaign http://www.bjcancer.com