 Nucleic acids, proteins and metabolites previously identified as candidate biomarkers of individual kidney graft lesions will be determined systematically in urine and blood samples collected in patients from the time of transplantation onwards, as well as in the graft tissue when biopsies are required for medical causes or performed systematically in the investigation centres. Their diagnostic and prognostic performance will be checked against histological reading of the biopsies and evolution of the graft function over time. 