Introduction: Opportunistic breast cancer screening associated with a better coverage for highest socio-economic status (SES) existed in Belgium before the introduction of a national screening program in 2001-2002. This work examined the changes in the mammographic coverage by SES and the changes in SE-inequalities since 1997.Methods: Data were obtained from the Health Interview Surveys (1997-2001-2004-2008). The mammographic coverage rate was computed for women aged 50-69. Educational levels (EL) were used as proxies for SES. SE-inequality for mammographic coverage was estimated with absolute and relative disparity measures (absolute differences and ratio of the lowest versus highest EL-prevalence), regression indices (the SII and RII), and the Population-Attributable Fraction (PAF). The evolution over time of the indices was measured by testing for the differences between the first and the last survey year, and by fitting a weighted linear regression.Results: In each EL a substantial increase in the coverage was observed over time. The relative increase of prevalence (absolute increase in prevalence between 2 years divided by the prevalence in the first year) between 1997 and 2008 was larger in the 2 less educated groups (respectively + 62.8% and +92.75% increase from initial value) than in the more educated groups (+ 33% and +19%). All inequality indices reflected a change towards less inequality: the absolute prevalence difference (lowest vs highest) decreased with 55% (p=0.13), the RR of being screened (lowest vs highest) increased with 40% (p=0.07) , the PAF decreased with 72% (p<0.01) , the RII increased with 76% (p=0.07) and the SII decreased with 52% (p=0.13). However, for most of the indices, no linear trend in SE-inequalities could be observed: only between 1997 and 2001 these inequalities seem to have been reducedDiscussion and Conclusions: Since 1997, the prevalence rates of mammographic coverage increased for every EL. At the beginning of the study period - before the introduction of the screening program - a reduction of SE-inequality could be observed. The figures reflect little improvement since its introduction.