Symptomatic upper-extremity deep venous thrombosis (UEDVT) after pacemaker placement in adults has been reported, but the occurrence of UEDVT in pediatric patients is poorly defined, and no treatment guidelines exist. This report describes a 14-year old girl with a history of complete atrioventricular block who experienced a symptomatic UEDVT 8 months after placement of a transvenous pacemaker. The girl was treated initially with anticoagulation including subcutaneous enoxaparin and a heparin drip, which did not resolve the venous obstruction. In the interventional laboratory, a venogram demonstrated complete obstruction of the left subclavian vein, which was treated successfully with catheter-directed alteplase, direct thrombus removal by manual suctioning, and balloon angioplasty. Warfarin therapy was continued for an additional 6 months, with follow-up venous ultrasounds demonstrating left subclavian vein patency. Soon after completing warfarin therapy, the girl presented with minimal edema of her left distal extremity and was thought to have post-thrombotic syndrome, which resolved quickly. She continued to receive aspirin therapy, with no recurrence of symptoms. In conclusion, symptomatic UEDVT after pacemaker placement in a pediatric patient can be treated successfully with both anticoagulation and interventional therapies. Further studies are needed to evaluate the incidence of thrombus formation among children with transvenous pacemaker placement together with the development of guidelines based on the safety and effectiveness of differing treatments.