Abstract Background Current out-of-hospital cardiac arrest (OHCA) prevention strategies are suboptimal due to the inability to identify subgroups at high risk. Insight into the occurrence of OHCA within general populations may help to target prevention strategies. Case registries suggest that there may be substantial differences in emergency medical service (EMS)-attended OHCA incidence between men and women. However, due to a lack of individual-level prospective data, relative sex differences across ethnic groups and socioeconomic (SES) groups have not been studied. Purpose We investigated sex differences in OHCA incidence, overall and across ethnic groups and SES groups. Methods We performed a retrospective population-based cohort study, combining individual-level data on ethnicity and income (as SES measure) from Statistics Netherlands of all men and women aged ≥25 years living in one study region in the Netherlands on 01–01–2009 (n=1,688,285) with prospectively collected EMS-attended OHCA cases (n=5,676) from the ARREST registry until 31-12-2015. We calculated age-standardised incidence rates of OHCA. Sex differences were assessed with Cox proportional hazards regression analyses, adjusted for age, ethnicity and income, in the overall population, and across ethnic and SES groups. Results Overall, the age-standardised incidence rate of OHCA was lower in women than in men (30.9 versus 87.3 per 100,000 person-years), corresponding with a hazard ratio (HR) of 0.33 (95% confidence interval [CI] 0.31–0.35). While incidence rates varied across subgroups (range: 22.6–104.6 per 100,000 person-years), the sex differences in hazard for OHCA existed in all income quintiles (HR range: 0.30–0.35) and ethnic groups (HR range: 0.19–0.40), except among Moroccans (HR 0.89, 95% CI 0.51–1.57). Conclusion In most ethnic groups and all SES groups, women have a substantial, yet lower OHCA incidence rate than men. This confirms that men are an important target group for OHCA prevention strategies across social strata. Nevertheless, considering potentially differential aetiology as well as the lower survival rates among women, women will also benefit from targeted prevention strategies. Funding Acknowledgement Type of funding sources: Public grant(s) – EU funding. Main funding source(s): European Union's Horizon 2020 research and innovation programme under acronym ESCAPE-NET (grant number 733381) and the COST Action PARQ (grant agreement number CA19137).ZonMw Gender and Health (grant number 8492ehab724.06458) and Gender and Prevention (grant number 555003016) programmes.