Bone fragility is a complication of chronic kidney disease (CKD). The aim of this study was to assess whether volumetric bone mineral density (vBMD) and microarchitecture could be impaired early in the course of CKD. Bone microarchitecture was examined with a noninvasive 3D imaging technique [high-resolution peripheral quantitative computed tomography (HR-pQCT)] at the tibia and radius in 70 stage II-IV CKD patients older than 50 years of age; controls belonged to two cohorts of healthy subjects comparable for age and gender (OFELY cohort in women and STRAMBO cohort in men). We examined 46 men and 24 women; 19 patients were diabetic. Mean age was 70.8 +/- 8.5 years, mean glomerular filtration rate (GFR) was 34 +/- 12 mL/min per 1.73 m(2), and mean serum parathyroid hormone (PTH) level was 87 +/- 59 pg/mL. Both CKD men and women experienced a moderate but significant trabecular (Tb) impairment, positioning CKD patient values between those of normal and osteopenic controls (e.g., CKD men versus healthy controls: Tb vBMD 172 +/- 35 versus 188 +/- 34 mg HA/cm(3); Tb number 1.75 +/- 0.27 versus 1.86 +/- 0.26 mm(-1), and Tb separation 503 +/- 94 versus 465 +/- 78 microm; p < .05). Cortical thickness (Ct.Th) in men also was significantly decreased compared with healthy controls (e.g., CKD men versus healthy controls: tibial Ct.Th 1171 +/- 331 versus 1288 +/- 283 microm; p < .05). In conclusion, this study, using a noninvasive bone-imaging device, shows for the first time an early impairment of trabecular microarchitecture in stage II-IV CKD patients. Further longitudinal studies should be performed to validate HR-pQCT as a tool for predicting the fracture risk in CKD.