participants, & measurements Our multicenter, prospective, observational study included 1553 patients with CKD (2009-2011). Carotid and femoral ultrasounds were performed at baseline and after 24 months. A subgroup of 476 patients with CKD was also randomized to undergo ultrasound examination at 12 months. Progression of atheromatosis was defined as an increase in the number of plaque territories analyzed by multivariate logistic regression. Results Prevalence of atheromatosis was 68.7% and progressed in 59.8% of patients after 24 months. CKD progression was associated with atheromatosis progression, suggesting a close association between pathologies. Variables significantly predicting atheromatosis progression, independent from CKD stages, were diabetes and two interactions of age with ferritin and plaque at baseline. Given that multiple interactions were found between CKD stage and age, phosphate, smoking, dyslipidemia, body mass index, systolic BP (SBP), carotid intima-n-iedia thickness, plaque at baseline, uric acid, cholesterol, 25-hydroxy vitamin D (250H vitamin D), and antiplatelet and phosphate binders use, the analysis was stratified by CKD stages. In stage 3, two interactions (age with phosphate and plaque at baseline) were found, and smoking, diabetes, SBP, low levels of 25OH vitamin D, and no treatment with phosphate binders were positively associated with atheromatosis progression. In stages 4 and 5, three interactions (age with ferritin and plaque and plaque with smoking) were found, and SBP was positively associated with atheromatosis progression. In dialysis, an interaction between body mass index and 25OH vitamin D was found, and age, dyslipidemia, carotid intima-media thickness, low cholesterol, ferritin, and uric acid were positively associated with atheromatosis progression. Conclusions Atheromatosis progression affects more than one half of patients with CKD, and predictive factors differ depending on CKD stage.