The kidney volume after transplantation was compared in two groups, one treated by conventional immunosuppression and the other receiving small amounts of ciclosporin (CsA) together with azathioprine and steroid (the so-called triple therapy). Fourteen pairs of donors and recipients were investigated in each group. The kidney volume was measured, using computed tomography (CT scan), before and after transplantation in the donors and after transplantation in the recipients during the allograft rejection-free period. The graft volume at 2-3 months after transplantation was smaller (215.9 +/- 30.9 ml, mean +/- SD) in patients who received small amounts of ciclosporin A (CsA) together with azathioprine and steroid than that (270.9 +/- 75.0 ml) in those treated by conventional immunosuppression. The remaining kidney in the donor after transplantation underwent a similar increase in volume in the conventional and triple therapy groups. It is suggested that even a small amount of CsA can significantly limit the compensatory renal growth.