Recently IgA nephropathy(IgAN) in transplanted kidney have been reported a more grave prognosis of the disease, which account for progressive allograft loss as 12-16%. But, the studies for the clinical significance and the prognostic factors of IgAN developed in transplanted kidney were not sufficient. We analyzed the frequency and the prognostic factors of IgAN developed in patients who underwent Kidney transplantation(KT) between January 1990 and October 1998. Total 231 renal biopsies was done. IgAN was diagnosed in 31 cases, and it was 13.4% of total cases and 24.4% of cases that acute rejection(AR) were excluded. After the 3 patients of IgAN was excluded due to combined AR, 28 patients were followed. The allograft dysfunction, which defined as serum creatinine at last follow-up was above 2.0 mg/dL, was observed in 10 patients(35.7%) and 4 patients(14.3%) of them had graft failure and restarted hemodialysis. The serum crcatinine and creatinine clearance at renal biopsy were significantly correlated with allograft dysfunction, also interstitial fibrosis, tubular atrophy and vascular fibrous intima1 thickening showed similar correlation with prognosis. In conclusion, when allograft dysfunction was developed, IgAN in transplanted kidney should be considered and if the evidences of elevated serurn creatinine and decresed creatinine clearence at biopsy, severe interstitial fibrosis and tubular atrophy, severe vascular fibrous intimal thickening were present, more closer follow-up and careful treatment should be taken.