Elevated concentrations of asialylated LDL (asialo-LDL) have been reported in patients with coronary artery disease (CAD). This may stimulate lipid accumulation in arterial intima cells and promote atherosclerosis. To investigate asialo-LDL as a potential risk-factor for coronary atherogenesis, we developed an antibody-lectin sandwich assay to measure levels in serum from CAD patients and age-matched control subjects. LDL was captured with an anti-apolipoprotein (apo) B antibody and asialylated oligosaccharides measured using the biotinylated D-galactose (D-gal) binding lectin, Ricinus communis agglutinin 120 (RCA120), and a streptavidin-alkaline phosphatase conjugate. For the control and atherosclerotic subjects, median [interquartile range (IQR)] values for total concentrations of asialo-LDL were 240mg/L (18O–310mg/L) and 220mg/L (186–390 mg/L), respectively (P=0·82). When expressed as a percentage of serum apo B-100, median (IQR) values were 18% (16–23%) and 19% (15–29%), respectively (P=0·78). These results suggest asialo-LDL has little value as a risk factor for coronary atherosclerosis.