To evaluate technical feasibility, complications, and clinical outcomes of endovascular thrombolysis for iliofemoral thrombosis at two tertiary-care children's hospitals. Institutional review board-approved retrospective review from March 2003 through June 2013 showed that venous thrombolysis for iliofemoral thrombosis was performed in 57 children (64 limbs) with a median age of 16.1 years (mean age, 14.5 y; range, 1.0-17.8 y). Techniques included catheter-directed thrombolysis (CDT), percutaneous mechanical thrombectomy (PMT), and pharmacomechanical catheter-directed thrombolysis (PCDT) with adjunctive angioplasty and/or stent placement. Villalta and modified Villalta scales were applied retrospectively to follow-up data to assess postthrombotic syndrome (PTS). Technical success (≥ 50% thrombolysis) rate was 93.7%: grade III (100%) in 19 limbs, grade II (50%-99%) in 41 limbs, and grade I (< 50%) in four limbs. Techniques included CDT with PCDT (32.8%) or PMT (35.9%), CDT alone (26.6%), PCDT alone (4.7%) or with adjunctive angioplasty (54.7%), and stent placement (6.3%). Mean duration of CDT was 36.5 hours (range, 2.9-89.6 h). There was one major complication (1.8%) of bleeding requiring transfusion. Minor complications (ie, bleeding) occurred in seven patients (12.2%). Median follow-up was 1.5 years (range, 30 d to 7 y). Seven patients underwent repeat thrombolysis for recurrent thrombosis. The PTS rate was 59.3% per modified Villalta scale but only 2.1% per Villalta scale. Endovascular thrombolysis is technically feasible and safe for iliofemoral thrombosis in children. Variable results were seen with two scales to assess PTS, suggesting an acute need for standardization of outcome measurement in children.