Trials have shown that breast cancer screening is effective in reducing breast cancer mortality and gaining life-years. The question is whether taking into account the impact of a screening programme on quality of life would lead to a less positive view. Screening may have effects on quality of life in the short run for women participating and effects in the long run as a result of the expected shift in the number of women experiencing early and advanced phases of the disease, after the initiation of the programme. In this study 4 steps have been taken: (I) published studies on quality of life and breast cancer (screening) up to 1989 have been reviewed and summarized and, based on these data, the consequences of breast cancer and treatment have been described; (2) values have been assigned to the disease and treatment phases by experts in breast cancer and public health (N = 31, response 87%); (3) these values have been inserted in the MISCAN model predicting the prevalence of disease/treatment phases with and without a 2-yearly screening programme for women aged 50-70 and multiplied by the duration of these phases; (4) analyses have been done to establish the sensitivity of the results for the values inserted. The programme of 2-yearly mammographic screening for women aged 50-70 is predicted to be 8% "less effective" (range -19.7 to +3.2%) when computing quality-adjusted life-years. We conclude that this adjustment is too small to attribute a major role to quality of life in the decision to undertake a large-scale breast cancer screening programme.