We experienced six cases whose one hour post-transplantation kidney biopsies showed mesangial IgA deposits. They were all living related transplantation recipients. The purposes of this study are; first, to evaluate whether the IgA deposits found in one hour biopsy specimens belong to the donors or it develop following transplantation, second, to assess the fate of the IgA deposits; and thirdly, to know if it happens the recurrence or de novo IgA nephropathy. We examined the biopsy specimens which were taken before and after the recirculation to the transplanted kidney in two cases. The findings of immunofluorescence method and electron micrographs in these two specimens were quite similar. This made sure that the IgA deposits seen in one hour biopsies were pathological findings of the donors who did not have abnormal urinalysis at donation. This suggests the families of the recipients may have subclinical IgA nephropathy. The fate of the mesangial IgA deposits are variable. It seems that the mesangial IgA deposits are fading gradually in at least two cases who do not have abnormal urinalysis following successful renal transplantation. But the deposits did not fade out completely up to 12 months. In three cases who develop abnormal urinalysis, the intensity of the IgA deposits became more dominant than one hour biopsy and biopsies that were taken during normal urinalysis following transplantation. We cannot make clear whether these manifestations show recurrence of IgA nephropathy or de novo nephritis because the original renal diseases before renal transplantation are not confirmed. However, their histories are compatible with those of renal failure secondary to IgA nephropathy. We concluded that probably in half of these patients the posttransplant renal changes are the recurrence of IgA nephropathy.