Background and aims: It is still unclear whether a healthy diet can prevent heart failure (HF). Therefore, this study aimed to investigate the association between adherence to a Mediterranean-style diet, reflected by modified Mediterranean Diet Scores (mMDS), and the incidence of HF in men and women. Methods and results: This observational study comprised 9316 men and 27,645 women from the EPIC-NL cohort free from cardiovascular disease at baseline. Dietary intakes were assessed using a validated food frequency questionnaire. mMDS was calculated using a 9-point scale based on consumption of vegetables, legumes, fruit, nuts, seeds, grains, fish, fat ratio, dairy, meat and alcohol. HF events were ascertained by linkage to nation-wide registries. Multivariable Hazard Ratios (HR) and 95% confidence intervals (CI) were estimated by Cox proportional hazards regression models. Over a median follow-up of 15 years (IQR 14–16), 633 HF events occurred: 144 in men (1.5%) and 489 in women (1.8%). The median mMDS was 4 (IQR 3–5). There was significant effect modification by sex (P-value for interaction <0.001), therefore results are stratified for men and women. For men, a higher mMDS associated with lower HF risk (HR: 0.88; 95% CI: 0.79, 0.98 per point increase in mMDS; HR upper category: 0.53; 95% CI: 0.33, 0.86), whereas no association was found in women (HR: 0.98; 95% CI: 0.93, 1.04 per point increase; HR upper category: 1.07; 95% CI: 0.83, 1.36). Conclusion: Adherence to a Mediterranean-style diet may reduce HF risk, particularly in men. The underlying reasons for the differences in findings between men and women need further study.