The hypothesis that chronic kidney disease (CKD) is associated with increased coronary artery calcification (CAC) was tested using data from the Dallas Heart Study, a representative sample of Dallas County residents aged 30 to 65 yr. CKD was defined as presence of microalbuminuria and GFR > or =60 ml/min per 1.73 m(2) (stage 1 to 2), or GFR <60 ml/min per 1.73 m(2) (stage 3 to 5), excluding end-stage kidney disease. Logistic regression was used to examine the association between stages of CKD and CAC scores >10, >100, and >400 versus scores < or =10 compared with no CKD while adjusting for covariates. Analyses were repeated after stratifying by presence of diabetes. The mean age was 43.9 yr, and hypertension and diabetes were noted in 31.0 and 9.8%, respectively. No association was noted between stage 1 to 2 CKD and increased CAC scores. Compared with no CKD, stage 3 to 5 CKD was associated with CAC scores >100 (odds ratio, 2.85; 95% confidence interval, 0.92 to 8.80) and >400 (odds ratio, 8.35; 95% confidence interval, 1.94 to 35.95) in the total population after adjustment for covariates, but these associations were substantially reduced after exclusion of participants with diabetes. Participants with diabetes and stage 3 to 5 CKD had a ninefold increased odds of CAC scores >10 versus scores < or =10 compared with participants with diabetes and without CKD, whereas no association was noted between stage 3 to 5 CKD and CAC scores >10 in the nondiabetic population. In conclusion, stage 3 to 5 CKD is associated with increased CAC scores, but this association may be substantially stronger among adults with diabetes. These findings need to be confirmed in study populations that include adults >65 yr of age and a larger number of CKD cases.