Background. Blood pressure (BP) control immediately after renal transplantation is poorly understood, with patients experiencing both high and low BP levels. Donor kidneys lack the ability to autoregulate their blood flow, meaning high pressures are directly translated to the graft endothelium, whereas reduced perfusion may augment ischemic injury. We hypothesize that early BP control may therefore influence the early alloimmune response. Methods. A total of 276 patients undergoing primary cadaveric renal transplantation who received cyclosporine-based therapy were followed; standard transplant variables were identified. BP was serially recorded before, during, and after reperfusion until 50 hr after surgery. Variables predicting acute rejection and delayed graft function were identified using Cox and logistic regression models. Results. The mean (SD) BP after surgery was 161(19) mm Hg systolic and 73(12) mm Hg diastolic. Forty-two percent had perioperative hypertension defined by conventional parameters. Increasing postoperative systolic BP, measured as standardized area-under-the-curve, was associated with an increased risk for acute rejection (hazard ratio [per mm Hg]=1.008), independent of other covariables including the preoperative BP level. Diastolic BP was inversely associated with the risk of delayed graft function (odds ratio [per mm Hg]=0.956). Conclusions. Early hypertension is common after renal transplantation. Early BP control has the potential to influence the risk of allograft rejection and delayed graft function.