The International Society of Nephrology and Renal Pathology Society Working Group revised the histopathological classification of lupus nephritis (LN) in 2003. We studied the clinical outcome of 39 children (85% female) aged 3.3-18.0 (median 13.7) years who underwent 49 percutaneous renal biopsies at 0.1-7.8 (median 1.0) years from diagnosis of systemic lupus erythematosus (SLE) at our centre over 10 years. All renal biopsies were reviewed and reclassified according to the new criteria by one histopathologist: 2%, 13%, 15%, 51% and 20% of all cases were classes I-V, respectively (with no cases of class VI LN) and 12% overlap cases (4% classes III and V, 8% classes IV and V). Patients were followed up for 1.3-15.4 (median 5.5) years with renal and overall survival rates of 90% and 92%, respectively. Half of the children with LN have features of class IV LN, with diffuse global (class IV-G) LN associated with the worst clinical outcome and the three most severe cases of chronic renal failure with estimated glomerular filtration rates (GFRs) <25 ml/min per 1.73 m(2) in patients with diffuse global sclerosing [class IV-G(C)] LN. The new classification allows expanded histopathological grading of LN with further delineation of classes III and IV with activity and chronicity indices.