Between 1968 and 1991, 36 pregnancies were reported in 28 patients who had undergone kidney transplantation at the Necker hospital, Paris. Pregnancies with favourable graft outcome were compared with those accompanied by significant deterioration of graft function and requiring haemolysis. The risk factors for renal function deterioration during pregnancy in kidney-transplanted women were found to be an initial nephropathy induced or aggravated by a previous pregnancy, an alteration, even mild, of graft function, hypertension, even controlled by treatment, an HLA mismatch and several episodes of acute graft rejection soon after kidney transplantation.