Clinical and laboratory features in 27 children and adolescents (24 females, 3 males) with lupus nephritis were analysed and correlated with pathohistologic findings obtained by renal biopsy. The mean age at the onset of the disease was 12.1 +/- 1.9 (range 0.1-7.0) years. In the 30% of patients nephritis was one of the presenting features of the disease. The most frequent signs of the lupus nephritis at the time of biopsy were proteinuria (9 pts), proteinuria and haematuria (9 pts), and nephrotic syndrome (8 pts), while 7 patients showed decreased glomerular filtration rate (GFR), and hypertension was present in five. Distribution of patients according to the WHO morphologic classification of Lupus nephritis was as follows: 6 pts showed class Ib, 6 class II, 2 class III and 13 class IV. More severe renal dysfunction, manifested by nephrotic syndrome, proteinuria with haematuria, decreased GFR and hypertension was significantly associated with proliferative lupus nephritis (combined WHO classes III and IV). Nephrotic syndrome, haematuria and decreased serum C3 with significant probability predicted proliferative lupus nephritis, while decreased GFR was of borderline predictive value.