BACKGROUND: Chronic kidney disease (CKD) is considered one of the most common risk factors for cardiovascular disease. Coronary artery calcification (CAC) is a potential mechanism that explains the association between renal function and cardiovascular mortality. We aimed to evaluate the association between renal function and CAC in apparently healthy Korean subjects. METHODS: A total of 23,617 participants in a health-screening program at Kangbuk Samsung Hospital were included in the study. Estimated glomerular filtration rate (eGFR) was assessed using the Cockcroft-Gault equation. Coronary artery calcium score (CACS) was measured via multidetector computed tomography. Subjects were divided into three groups according to the CKD Staging system with eGFR grade: stage 1, eGFR > or =90 mL/min/1.73 m2; stage 2, eGFR 60 to 89 mL/min/1.73 m2; and stage 3, eGFR 30 to 59 mL/min/1.73 m2. RESULTS: The mean age of the participants was 41.4 years and the mean eGFR was 103.6+/-21.7 mL/min/1.73 m2. Hypertension and diabetes were noted in 43.7% and 5.5% of the participants, respectively. eGFR showed a weakly negative but significant association with CACS in bivariate correlation analysis (r=-0.076, P<0.01). Mean CACS significantly increased from CKD stage 1 to 3. The proportion of subjects who had CAC significantly increased from CKD stage 1 to 3. Although the odds ratio for CAC significantly increased from stage 1 to 3 after adjustment for confounding factors, this significance was reversed when age was included in the model. CONCLUSION: In early CKD, renal function negatively correlated with the degree of CAC in Korean subjects. Age was the strongest effector for this association.