Purpose: To evaluate technical details, clinical outcomes, and complications in patients undergoing geniculate artery embolization for treatment of spontaneous hemarthrosis after knee surgery., Materials and Methods: During 2009-2014, 10 consecutive patients (seven women; mean age, 57.4 y) underwent geniculate artery embolization at a single tertiary care center. All patients except one had hemarthrosis after total knee replacement (TKR). One patient presented with hemarthrosis after cartilage surgery. Two patients in the TKR group had a history of TKR revisions before the embolization. Embolization was performed with polyvinyl alcohol particles (range, 300-700 µm). In one patient requiring repeat embolization, N-butyl cyanoacrylate/ethiodized oil was used. The endpoint for embolization was stasis in the target artery and elimination of the hyperemic blush., Results: In 10 patients, 14 embolizations were performed with 100% technical success. Hemarthrosis resolved in six patients. Four patients required repeat embolization for recurrent hemarthrosis, which subsequently resolved in two of four patients. Three of the four patients who required repeat embolization had serious comorbidities, either blood dyscrasias or therapeutic anticoagulation. There were two minor skin complications that resolved with conservative management. The average length of follow-up after embolization was 545 days (range, 50-1,655 d). One patient was lost to follow-up., Conclusions: Geniculate artery embolization is a safe, minimally invasive treatment option for spontaneous and refractory knee hemarthrosis after knee surgery with 100% technical success. However, limited clinical success and higher repeat embolization rates were noted in patients with serious comorbidities., (Copyright © 2016 SIR. Published by Elsevier Inc. All rights reserved.)