We retrospectively evaluated renal outcome in a total of 38 children and adolescents with IgA nephropathy who were selected for 6-month therapy for clinical (proteinuria > 1 g/m2/24 hour) and pathologic (mesangial proliferation, crescent formation, and tubulo-interstitial changes) features suggestive of progressive renal failure. Seventeen patients (group A) were treated with a combination of prednisolone, cyclophosphamide and dipyridamole, and the remaining patients (21; group B) were treated with the same drugs plus warfarin. All the patients were followed-up for more than 2 years (range 2-10 years, mean 4.8). In both groups, the mean urinary protein excretion value was significantly reduced after the therapy, compared with that at entry into the therapy. The significant reduction continued for up to 6 years in group A and up to 5 years in group B. Creatinine clearance was stable until 5-6 years after the trial in both groups, but 4 patients progressed to end-stage renal failure after that period. Post-therapy biopsy was performed in 14 patients, and was compared with the pre-therapy biopsy. The activity score had improved in both groups, but the chronicity score did not. These results indicate that there was a temporary effect and limited benefit with this treatment of combined drugs for children and adolescents with IgA nephropathy. The additive effect of warfarin was not substantiated.