['To investigate whether endothelial lipase (EL) plasma levels are increased in stable coronary artery disease (sCAD) and acute coronary syndrome (ACS) patients, as well as to test the association of EL plasma levels and the severity of CAD and sex.', 'The study was performed as a single-center, cross-sectional, observational research on 72 sCAD and 187 ACS patients in the Sisters of Charity University Hospital Centre, Zagreb, Croatia, between December 1, 2011 and December 1, 2012. EL plasma levels were measured using ELISA.', 'EL plasma levels were significantly higher in sCAD patients (median 311.3 pg/mL, interquartile range [IQR] 250.4-422.6 pg/mL) than in ACS patients (median=258.7 pg/mL, IQR=162.1-356.0 pg/mL; P<0.001). EL levels in female ACS patients were significantly higher (median 314.5 pg/mL, IQR 218.3-420.8 pg/mL) than in male ACS patients (median 225.4 pg/mL, IQR 148.7320.1 pg/mL; P<0.001) and similar to the EL levels in the sCAD patients. There was no significant correlation between EL plasma levels and the GENSINI score and between EL plasma levels and the number of atherosclerotic coronary artery segments in either the ACS (rho=-0.09, P=0.247; rho=0.12, P=0.106, respectively) or sCAD group (rho=0.04, P=0.771; rho=0.06, P=0.643, respectively).'] Are endothelial lipase plasma levels increased in both sexes in stable coronary artery disease and only in women with acute coronary syndrome but not associated with the severity of coronary artery disease?