Macrolevel gender inequality is defined as the unequal distribution of power and resources between men and women shaped by macrolevel social structures and institutions. An emerging line of health research is emphasising its negative consequences on women's health and healthcare access. The present study examines how gender inequality contexts affect women's mammography screening uptake. It adopts a macrosociological and institutionalist approach on preventive healthcare use and compares women who live with a partner with those who do not. This is the first study to test the effect of macrolevel gender inequality on mammography uptake across the 26 Swiss cantons (i.e. regions). The Swiss cantons' autonomy to manage their political and healthcare systems, as provided by the federal system, offers an ideal setting for the comparative analysis of macrolevel factors. Data on 9724 women aged 50–70 from the Swiss Health Interview Survey (waves 2007, 2012 and 2017) is analysed. Multilevel logistic models estimate two canton-level indicators of gender inequality, the gender gaps in time use and full-time employment, and their association with mammography uptake, controlling for women's socioeconomic and demographic characteristics, health status and healthcare use. Cross-level interactions assess how these indicators moderate the mammography uptake of women living with and without a partner. Results show that in cantons with higher gender inequality, women have a lower probability of mammography uptake. Women who live with a partner have a higher mammography uptake than those who do not. However, this advantage is moderated by canton-level gender inequality, namely, women who live with a partner in more gender unequal cantons have a lower mammography uptake than their counterparts who reside in more gender equal cantons. Results support the hypothesis that macrolevel gender inequality moderates women's preventive healthcare uptake, from an institutionalist approach.