Background - LDL-cholesterol (LDL-C)/apolipoprotein B (Apo B) ratio has been reported to be associated with cardiovascular risk factors and the prevalence of metabolic syndrome. The aim of this study was to assess the independent association between LDL-C/Apo B ratio and incident metabolic syndrome in Korean men. Methods and Results - This study included 514 men (mean age: 49 years) without metabolic syndrome at baseline who were followed for an average of 2.9 years. Subjects were divided into four groups according to LDL-C/Apo B ratio quartiles (>1.243 in group I; 1.164-1.243 in group II; 1.070-1.163 in group III; <1.070 in group IV). Metabolic syndrome was defined using the the National Education Program (NCEP) Adult Treatment Panel III criteria. The overall incidence of metabolic syndrome was 10.3%: 1.6% in the highest (group I), 10.1% in group II, 12.4% in group III, and 17.2% in the lowest quartile (group IV) (p<0.001). In the multivariate regression models, group II, III, and IV had significantly increased odds for incident metabolic syndrome as compared with group I, independently of age, body mass index, lifestyle status, homeostasis model assessment of insulin resistance (HOMA-IR), and diabetes mellitus. Conclusion - LDL-C/Apo B ratio is significantly associated with incidence of metabolic syndrome in Korean men, indicating that LDL-C/Apo B ratio could provide additional information in assessing the cardiometabolic risks and future metabolic syndrome.