Percutaneous liver biopsy is an important diagnostic tool for the management of patients following liver transplantation. However, it may be associated with severe complications. To evaluate the incidence and type of complications after liver biopsy, we retrospectively analyzed 919 patients who underwent orthotopic liver transplantation (OLT) from September 1988 to May 1998. A total 3,670 biopsies were performed with ultrasound guidance and use of the Menghini needle (1.6 mm diameter). The biopsies were performed according to the protocol on the 7th postoperative day and one, three, five years after OLT, or when clinically indicated. Patients with severe coagulopathy (thrombocytes < 30,000/nl and Quick < 40%) were excluded from this protocol. Biopsy was complicated by bleeding in 13 of 919 patients (1.41%). The incidence of procedure related complications was 13 of 3,670 (0.35%). Five patients showed intrahepatic hematoma, four patients developed a hematothorax, three patients had intraabdominal bleeding and one patient suffered from hemobilia. Seven of 13 patients (53%) required surgical intervention (laparotomy four, thoracotomy two, retransplantation one). Graft dysfunction after liver transplantation requires rapid assessment and specific treatment to achieve good results. Percutaneous liver biopsy is an important procedure in the evaluation and identification of graft dysfunction such as acute rejection, hepatitis reinfection or toxic alterations. From our data we conclude that percutaneous liver biopsy is a safe procedure and advocate is liberal use.