The authors present the case of a 3-year-old boy who had transient ischemic symptoms secondary to thromboembolism from a left brachial artery aneurysm not associated with trauma or an autoimmune or connective tissue disorder. He underwent emergency resection of a brachial artery aneurysm and interposition grafting. Two months later he was found to have a right brachial artery aneurysm and underwent elective aneurysm resection and interposition grafting. He was well at the 3-year follow-up and had no other arterial aneurysms. The risk of limb threat or loss can be avoided by prompt diagnosis and early surgery. The authors advocate brachial artery aneurysm resection when it becomes technically feasible and/or when thrombus is present. Patients with upper extremity aneurysms should have continuous follow-up with serial examinations to detect concomitant or subsequent aneurysm formation.