Until 1997, breast screening by mammography was free for all women living in Turku, Finland. After this date, women born in certain years had to pay to be screened. We did a retrospective study, using data obtained from Statistics Finland, to ascertain whether or not the introduction of a fee affected attendance. We also assessed the effect of socioeconomic status on attendance. Our findings show that people who had to pay for mammography attended less often than women who were entitled to free screening, irrespective of their socioeconomic status.