We investigated the incidence and types of liver biopsy complications in our first 160 consecutive liver transplantations. A significant complication was identified by the need for therapeutic intervention (for example, hospitalization, transfusion, intravenous fluids, chest tube, surgery or antibiotic therapy). A total of 950 percutaneous hepatic allograft biopsies were performed in 136 patients (mean = 6.9 biopsies/graft; range = 1 to 29). A significant complication was reported after 17 (1.8%) liver biopsies in 13 (9.6%) patients. Bleeding complications occurred in 11 patients and serious infection developed in 6 patients, but all patients recovered with appropriate therapy. Of special interest was that five of six patients with infectious complications had undergone Roux-en-Y choledochojejunostomy as part of the transplantation operation. The incidence of infectious complications related to a series of biopsies was significantly greater in patients who underwent choledochojejunostomy (12.5%) than in patients who underwent duct-to-duct biliary anastomosis (1%) (p less than 0.01). Furthermore, all septic events in patients who underwent choledochojejunostomy were related to enteric organisms. This investigation reaffirms the safety and low incidence of complications related to percutaneous liver biopsy even in this unique patient population. However, we did identify a subgroup of patients with biliary-enteric anastomoses who appear to be at increased risk of septic complications after liver biopsy. Antibiotic prophylaxis at the time of liver biopsy may be appropriate in this high-risk subgroup to decrease the frequency of infectious complications.