Abstract Apolipoprotein B (apoB) concentration reflects the number of atherogenic particles and is closely associated with atherosclerosis. Non-HDL-cholesterol (non-HDL-C) has been considered a therapeutic target for patients with hypertriglyceridemia. We compared the predictive values of apoB and non-HDL-C for the metabolic syndrome (MetS) in 3335 Korean adults (mean age, 45.2 years) who participated consecutively in a health examination in a university hospital. Anthropometry, blood pressure, fasting glucose, lipid profiles and apoB were measured. MetS, as defined by a modification of the NCEP-ATP III criteria, was present in 22.1% of men and 16.1% of women. Among the components of the MetS, triglycerides showed the strongest correlation with apoB ( r = 0.393, P < 0.001 in men, and r = 0.326, P < 0.001 in women) and non-HDL-C ( r = 0.376, P < 0.001 in men, and r = 0.349, P < 0.001 in women). When apoB and non-HDL-C were mutually adjusted, the ORs for the MetS of non-HDL-C were not significant. As a function of the quartile of apoB levels, the ORs for the MetS were 2.04 (1.26–3.30), 3.54 (2.11–5.93), and 5.38 (3.16–9.17) in men ( P for trend <0.001) and 3.75 (1.42–9.87), 5.55 (2.09–14.69), and 13.41 (5.02–35.79) in women ( P for trend <0.001), respectively. These findings indicate that apoB is a better marker than non-HDL-C for identifying the MetS among Koreans.