The present study evaluated the association between long-term, exclusive olive oil consumption, in cooking preparation or as a dressing, and the 10-year (2004-2014) incidence of acute coronary syndrome (ACS) among cardiac patients.From October 2003 to September 2004, a sample of 2172 ACS consecutive patients from six major Greek hospitals were enrolled. During 2013-2014, the 10-year follow-up was performed in 1918 patients (88% participation rate). The development of fatal or nonfatal ACS was recorded through medical records or hospital registries. Among other dietary components, added fats (i.e. olive oil, butter, margarine and seed oils) consumption at baseline examination was assessed using a semi-quantitative food frequency questionnaire.Non-exclusive olive oil consumption on a daily basis was associated with an adverse effect on the ACS incidence after taking into account various potential confounders [odds ratio (OR) = 1.40, 95% confidence interval (CI) = 1.05-1.86, P = 0.024]. However, significant interactions between olive oil consumption and body mass index (BMI) (P = 0.082) and educational level (P = 0.054) led to further stratified analysis. Using BMI as strata (i.e. ≤29.9 versus >29.9 kg m(-2)), the above association remained significant only in obese patients (OR = 1.80, 95% CI = 1.03-3.12, P = 0.038), whereas, on examining the education status (i.e. ≤9 versus >9 years of school), a significant association was observed only among the higher educated patients (OR = 1.83, 95% CI = 1.01-3.32, P = 0.047).Exclusive use of olive oil, either as a salad dressing or in cooking, should be promoted through the dietary management of ACS patients, with the aim of reducing the likelihood of recurrent cardiac episodes.