We report the case of a 25-year-old female with renal arteriovenous fistula and pseudoaneurysm (PA) formation following renal core-needle biopsy, treated successfully by ultrasound-guided percutaneous embolization with autologous blood clot injection. After inserting a 15-gauge needle within the PA sac, 10 ml of blood was retrieved from the sac, and then reinjected into the PA as well as in the needle tract after the obtained blood completely clotted. The procedure was completed by manual compression of the flank. Follow-up sonographic examinations revealed no complication, and the PA size reduced gradually over time due to fibrotic shrinkage. © 2017 Wiley Periodicals, Inc. J Clin Ultrasound 45:592-596, 2017.