Percutaneous large bore cannula placement during orthotopic liver transplantation (OLT) for use in venovenous bypass (VVB) has been reported to be a rapid and simple technique. It is, however, a technique that carries its own risks. The aim of the study was to investigate the incidence of complications related to the placement of a percutaneous venous return cannula and subsequent VVB in OLT. A retrospective review of 360 consecutive adult OLT patients during a period of 18 months (January 1, 2003 to June 30, 2004) was performed. The percutaneous venous cannula (18 Fr) was placed by an attending transplant anesthesiologist. The cannulation was attempted in 326 patients (90.6%). No cannulation was attempted on the subclavian veins. Internal jugular venous cannula placement was attempted but aborted in 6 patients (1.8%) due to technical difficulties. In 320 patients who received an internal jugular venous cannula, 313 (97.8%) underwent OLT without complication. The remaining 7 patients (2.2%) had complications. The operation was delayed for 1 patient due to suspected hemomediastinum. The other 6 complications were related to VVB: air embolism (2 patients), low flow rate (2 patients), hypotension (1 patient), and atrial fibrillation (1 patient). Successful OLT was eventually carried out in all the 7 patients and no mortality associated with internal jugular venous cannula placement or VVB was noted. In conclusion, percutaneous placement of a large bore venous return cannula for VVB during adult OLT can be performed with acceptable risk using a flexible 18-Fr cannula via the right internal jugular vein (IJV) by experienced attending transplant anesthesiologists.