Increased intima-media thickness of the carotid arteries (cIMT) has been found in young adults with childhood-onset chronic kidney disease (CKD). The disease stage at which these patients first develop abnormalities of arterial texture is unknown. The objective of this study was to determine the onset and character of arterial changes in children aged 10 to 20 yr with different stages of CKD and to identify risk factors for early arteriopathy. High-resolution ultrasonography was conducted of common cIMT and femoral superficial artery IMT. Fifty-five children with stages 2 to 4 CKD (GFR 51 +/- 31 ml/min per 1.73 m2), 37 on dialysis, and 34 after renal transplantation (Rtx; GFR 73 +/- 31 ml/min per 1.73 m2) were studied. Control subjects were 270 healthy children, matched for age and gender. Compared with control subjects, cIMT, femoral superficial artery IMT (both as absolute values and as SD score of median of normal value), wall cross-sectional area, and lumen cross-sectional area of carotid artery were significantly increased in all patient groups and most markedly abnormal in dialysis patients. cIMT in CKD and Rtx patients was significantly lower in comparison with dialysis patients. cIMT correlated with mean past serum Ca x P product, the cumulative dose of calcium-based phosphate binders, and the time-averaged mean calcitriol dose. The cumulative phosphate binder intake, time-averaged Ca x P product, and young age were independent predictors of an increased cIMT. In children with CKD, thickening of IMT occurs early in the course of disease and is most marked in dialyzed patients. The changes may be partly reversible after Rtx.