In 53 children and adolescents (47 males, 6 females) with lupus nephritis, clinical features at the time of renal biopsy were analyzed and correlated with pathohistological findings. The mean age at the time of diagnosis of systemic lupus was 12.9 +/- 2.6 (SD) years; the mean ages at the time of diagnosis of lupus nephritis and renal biopsy were 13.5 +/- 2.6 and 13.6 +/- 2.5 years, respectively. The most frequent clinical and laboratory features of lupus nephritis at the time of biopsy were proteinuria (100% of patients), haematuria (88%), nephrotic syndrome (38%), hypertension (32%), and decreased glomerular filtration rate (26%). On initial biopsy, the most frequent finding was diffuse proliferative glomerulonephritis (in 64.1%), followed by "mesangiopathy" (20.8%), minimal changes (7.5%), membranous nephropathy (5.8%), and focal proliferative nephritis (1.9%). Nephrotic syndrome, hypertension, decreased glomerular filtration rate, and haematuria were significantly associated with WHO classes IV and III of lupus nephritis.