['To explore a new predictor of renal flares after successful inductive treatment for diffuse proliferative glomerulonephritis(DPGN) in patients with lupus nephritis.', 'A cohort of patents with SLE DPGN who were treated initially with prednisone and cyclophosphamide were studied. Those who responded to inductive treatment were followed up for the occurrence of renal flares. Urinary levels of RANTES, MCP-1 and M-CSF were measured by ELISA. Other clinical and laboratory data were collected. The predictors and outcome of renal flare were analyzed.', 'Seventy-three qualified patients with SLE DPGN were investigated. After a mean follow-up of 24.5 +/- 6.4 months, 22 patients experienced renal flares. The median time to relapse was 14.1 +/- 4.1 months. The patients experiencing renal flare showed higher urinary RANTES, MCP-1 and M-CSF. However, independent predictors of renal flares were increased urinary RANTES and M-CSF. Eight patents developed doubling of the serum creatinine (CRX2) level. The occurrence of renal flares was the only predictor of CRX2.'] Are urinary levels of RANTES and M-CSF predictors of lupus nephritis flare?