Platelet derived growth factor (PDGF) possesses diverse biological activities and plays an important role in the pathogenesis of glomeruli nephritis. In order to elucidate the relationship between PDGF and the disease activation in lupus nephritis, PDGF was observed in renal biopsy specimen from 9 cases of lupus nephritis (7 cases with active and 2 cases with inactive lesions) by immunohistochemistry using 4-layer PAP method. The mRNA expression of PDGF-A and -B chain, and the receptor of PDGF-B were analyzed by RT-PCR. It was found that the levels of mRNA expression of PDGF and its receptor were much higher in patients with active lesions in glomeruli as compared with those without active lesions, there changes were paralleled with the degree of hematuria in these patients. Noted that there was no correlation between the expression of PDGF and the cellular proliferation in glomeruli of lupus nephritis. These results indicate that PDGF is a critical mediator for inducing active lesion in glomeruli of lupus nephritis. The effect of PDGF antagonist in the regulation of glomerular damage in lupus nephritis need to further elucidate.