BACKGROUND: The clustering of cardiovascular risk factors is known as insulin resistance syndrome. Hyperinsulinemia has been suggested as a cardiovascular risk factor due to the capacity of insulin to induce vascular endothelial proliferation and atherosclerosis. Insulin also has been shown to stimulate erythroid colony formation independently of erythropoietin. WBC count is one of the major components of the inflammatory process and is increased by IL-6, which is high in those with features of insulin resistance. In this study, we investigated whether insulin resistance affects hematological parameters. METHODS: In this study, 1,314, randomly selected, non-diabetic, elderly subjects over 60 years living in the southwest area of Seoul were recruited. Subjects underwent 75 g OGTT and careful physical examinations during evaluation, and were interviewed using a standardized questionnaire. Biochemical data and hematologic parameters were also measured. Insulin resistance was calculated by HOMA (homeostasis model assessment) method. Analysis of variance, Duncan's multiple comparisons and multiple linear regression analysis were carried out. RESULTS: In the male non-smoking group we found a correlation between insulin resistance and hemoglobin concentration (r=0.20, p=0.0186). In the female non- smoking group we found correlations between insulin resistance and both hemoglobin concentration (r=0.10, p=0.0017) and white blood cell (WBC) count (r=0.15, p=0.001). Hemoglobin concentration and WBC count were also correlated with BMI, systolic and diastolic blood pressure, lipid profiles and fasting insulin levels in female non-smokers. In multiple regression analysis, using HOMA IR as a dependent variable, we found significance in the variables of hemoglobin concentration, WBC count, age, BMI and triglyceride level. CONCLUSION: Our study provided evidence for a relation between insulin resistance and hematological parameters such as hemoglobin concentration and WBC count in elderly Koreans. This suggests that increased hemoglobin level and WBC count could be considered as novel aspects of the met.