The pathogenesis and the natural course of CV comorbidity in pediatric CKD patients is still elusive. In this multicenter, prospective, observational study the prevalence, degree and progression of CV comorbidity in children will be characterized and related to CKD progression. The morphology and function of the heart and vessels will be monitored by sensitive, non-invasive methods and will be compared with aged matched healthy controls. Multiple potential clinical, anthropometric, biochemical, and pharmacological risk factors will be monitored prospectively and will be related to CV status. Genotyping might identify predisposing genetic factors for progression of CV comorbidity and underlying nephropathies.