The influence of the implantation technique on the outcome was studied prospectively in a series of 116 consecutive adult patients undergoing primary liver transplantation during the period January 1991-June 1994. Thirty-eight patients (32.8%; group 1) underwent classical orthotopic liver transplantation (OLT) with replacement of the recipient's inferior vena cava (R-IVC) and with venovenous bypass (VVB). Thirty-nine patients (33.56%) had a piggy-back OLT with preservation of the R-IVC (group 2); bypass was used in 17 of them (43.6%) because of poor hemodynamic tolerance of R-IVC occlusion. Thirty-nine patients (33.6%) had OLT without VVB and with side-to-side cavocaval anastomosis (group 3). The three techniques were performed irrespective of the anatomical situation and of the status of the recipient at the time of transplantation. The following parameters were assessed in all patients: implantation time, blood product use, morbidity (e.g., hemorrhagic, thoracic, gastrointestinal, neurological, and renal complications), and outcome. Thirty-one patients underwent detailed intraoperative hemodynamic assessment. The early (< 3 months) post-transplant mortality of 10.3% (12/116 patients) was unrelated to the implantation technique. Group 3 had a significantly shorter mean implantation time, a reduced need for intraoperative blood products, and a lower rate of reoperation due to intra-abdominal bleeding. After excluding two immediate perioperative deaths and eight patients requiring early retransplantation because of primary nonfunction, the frequency of immediate extubation was significantly higher in group 3. Detailed hemodynamic assessment did not show a difference between 6 group 1 patients and 17 group 3 patients, indicating that partial lateral clamping of the IVC fulfills the function of venous bypass. Similar results were obtained in 6 group 2 patients who did not have IVC occlusion. Cavocaval OLT has become our preferred method of liver implantation. It allows the transplantation to be performed without VVB, regardless of the anatomical situation and of the condition of the patient at the time of transplantation. Moreover, it avoids all of the potential complications and costs of VVB.