Ultrasound-guided percutaneous thrombin injection has been developed as a less invasive and highly successful treatment of iatrogenic femoral pseudoaneurysms. Most of these lesions have been the result of catheterization procedures. This method has proved to be highly effective, and few complications have been reported. Specifically, native arterial thrombosis, although recognized as a severe complication, has been mentioned only briefly in the literature. We present a case of the successful management of native arterial thrombosis after attempted percutaneous thrombin injection of a chronic external iliac artery pseudoaneurysm. This case serves to illustrate the risk factors for this complication and the treatment options once it occurs. The success of this treatment with acute iatrogenic femoral pseudoaneurysms may not necessarily translate into similar success in other anatomic locations and clinical situations.