Liver biopsy is a frequently utilized diagnostic tool at a liver transplant center. It is occasionally utilized prior to OLTx to determine whether or not a potential recipient either has tumor or a disease process that has some chance of spontaneous recovery without OLTx. Following OLTx, it is often utilized to determine the need to alter a recipient's immunosuppression regimen or gauge the response to a recent change in immunosuppression. At the University of Pittsburgh Medical Center, adult liver transplant patients have been biopsied using 3 different techniques based upon the physician's (Tru-cut needle) or surgeon's (suction needle) personal choice and whether or not it has been the intent of the biopsy to obtain tissue from a focal lesion within a liver. In the latter cases, ultrasound guidance and an automated biopsy needle are used. In the former, either a suction-type needle (Jamshidi) or a cutting needle (Tru-cut) has been used. During the period between January 1, 1989, and December 31, 1991, a total of 12,750 liver biopsies have been done on patients admitted to the adult transplant service at this institution. Of these, 8500 were performed with a suction needle, 4195 were performed using a cutting needle, and 55 were performed under ultrasound guidance using an automated cutting needle. A total of 26 major complications occurred--19 with the suction needle (0.22%); 6 with the cutting needle (0.14%), and 2 using ultrasound guidance and an automatic cutting needle (3.6%). Nine of these 26 complications required surgical intervention consisting of a thoracotomy or laparotomy; 4 required the insertion of a chest tube and two required hepatic artery embolization. Based upon these data obtained at a large transplant center, it can be concluded that, in general: (1) a liver biopsy can be done safely in liver transplant recipients; (2) an overall low rate of major complications occurs varying from 0.1 to 3.6% depending upon the type of needle and other circumstances relating to the biopsy procedure; (3) complications, when they occur, are morbid and often necessitate either additional surgical or interventional radiologic procedures.