In our institution, systematic renal graft biopsies are performed 1 year after transplantation before deciding to switch to alternate-day steroid therapy, which has been shown to be beneficial for statural growth. We analyzed the results of systematic graft biopsies in 145 children with a creatinine clearance > or =45 ml/min per 1.73 m2. Biopsies were classified according to Banff diagnostic categories. Normal parenchyma was observed in 19 cases (13%), non-specific lesions in 42 cases (29%), chronic allograft nephropathy grade 1-3 in 68 cases (49%), and acute rejection in 8 cases (5%). Clinicopathological correlations indicated that patients with chronic allograft nephropathy had received kidneys from older donors, with longer cold ischemia time and with a higher incidence of delayed graft function. There was a strong correlation between the donor age and the presence of vascular lesions. There was also a good correlation between the severity of histological lesions and the occurrence of acute rejection episodes during the 1st year after transplantation. Renal function remained stable for up to 10 years in patients with normal parenchyma or non-specific lesions, while serum creatinine levels increased after the 2nd year in patients with chronic allograft nephropathy.