Increasing number of female kidney recipients deciding to born a baby makes us to investigate the impact of pregnancy on graft survival. The aim of study was to find the parameter that would have the predictive value for graft function following delivery. Scr and P in 33 pregnant renal allograft recipients (mean age 27.1 +/- 6.1 yrs) treated with pred + aza + CsA were studied for 6 mo before, during and 6 mo following delivery. As measured only by Scr graft function was stable in all pts (1.4 +/- 0.05 mg/dl). Significant rise in Scr following pregnancy was found in 6 of 33 pts. This "unstable" group was compared with 27 patients with "stable" despite pregnancy graft function. Proteinuria, but not Scr differentiated groups prior to pregnancy. The estimation of P prior to conception seems to be more potent parameter to predict kidney graft deterioration following pregnancy than Scr alone. Increase in P during and following pregnancy in "unstable" pts may reflect the acceleration of subclinical (not yet manifested with rise of Scr) chronic graft rejection due to pregnancy-induced hiperfiltration.