The recipient's hemodynamic condition during anesthesia for renal transplantation has a major influence on the early diuresis of the graft. The effect of maximal hydration during operation was studied in a series of 120 primary human cadaver kidney transplantations performed under peroperative monitoring of the pulmonary arterial pressures (PAPs). The PAPs levels before and at the time of clamp release were correlated with the frequency of postoperative acute tubular necrosis (ATN). The 120 patients were divided in two groups according to the PAPs levels before release of the vascular clamps: group 1 (22 patients) with a mean PAP (PAP) of less than or equal to 20 mm Hg and a diastolic PAP (DPAP) of less than or equal to 15 mm Hg was compared with group 2 (98 patients) with a PAP of greater than 20 mm Hg and a DPAP of greater than 15 mm Hg. Both groups were comparable with regard to the donor's data and the quantity of peroperative fluids. The frequency of ATN was 36% in group 1 versus only 6% in group 2. This difference is attributed to the different hemodynamic conditions in both groups: at the beginning of the transplant procedure, PAP, DPAP, and central venous pressure (CVP) were higher in group 2; at the time of clamp release, PAP, DPAP, CVP, and systolic blood pressure (SBP) were also higher in group 2. This study emphasizes the importance of the PAPs levels at the time of release of vascular clamps to avoid postoperative ATN of a kidney transplant.