OBJECTIVES:To examine the association between a dietary fat quality index (FQI), and the risk of incident cardiovascular events or deaths in the Seguimiento Universidad de Navarra (SUN) cohort. DESIGN:Longitudinal analysis during 10.1 years of median follow-up. Cox models were used to estimate adjusted hazard ratios (HR) of incident cardiovascular diseases (CVD) according to tertiles of FQI and of different fat subtypes. SETTING:University of Navarra, Spain. PARTICIPANTS:19,341 middle-aged adults. MEASUREMENTS:Fat intake was measured with a validated food-frequency questionnaire. The FQI was calculated according to the ratio: (monounsaturated+polyunsaturated) / (saturated+trans fatty acids). RESULTS:We observed 140 incident cases of CVD. No association was found for FQI (HR=0.94, 95 %CI 0.61-1.47 for the highest vs the lowest tertile, p for trend=0.884). No significant associations were found for different dietary fat subtypes on CVD risk. The results suggest no clear association between a higher FQI and a higher amount of energy from fat and incidence of CVD (p for interaction: 0.259 and p for trend only among participants with a percentage of energy from fat ≥35% of total energy: 0.272). CONCLUSION:In this Mediterranean cohort, the FQI was not associated with cardiovascular events. A "heart-healthy diet" should focus its attention on dietary fat sources and should use an overall dietary pattern approach, rather than limiting the focus on fat subtypes. More research is needed to validate dietary advice on specific fatty acids intake or saturated fatty acids replacements for reducing CVD risk.