Delayed subcapsular hematoma after percutaneous liver biopsy as a manifestation of warfarin toxicity. Guidelines for the management of patients receiving chronic anticoagulation therapy who require liver biopsy are not clearly defined. In patients with normal coagulation, liver biopsy is a relatively safe procedure with a morbidity of less than 0.1% and a mortality of less than 0.01%. We report a patient with a prosthetic aortic valve who developed a large subcapsular hematoma 12 days after a percutaneous liver biopsy as a consequence of warfarin toxicity. Based on the experience with this patient, reinstitution of anticoagulant therapy should be avoided for at least 72 h after a percutaneous liver biopsy. Intravenous heparin should be resumed first, and warfarin added if no bleeding has occurred after an additional 48-72 h. The prothrombin time should be maintained at 1.5 times the baseline. 