Compartment Syndrome refers to a medical condition where pressure within a confined space, surrounded by muscles and fascia, increases to a level that it damages muscles, blood vessels, nerves, and other structures. We would like to report a case in which the development of collateral flow due to outflow venous stenosis of a arteriovenous access caused compartment syndrome. The brachial vein, one of the deep veins of the upper extremity, has many side branches and is located within the same fascia as the brachial artery, making it the last option for arteriovenous access. This patient did not have a superficial vein to create an arteriovenous access, necessitating the creation of an AVG using a prosthetic graft. Given his young age, a forearm U-loop AVG was chosen over an upper arm straight AVG. The patient had persistent arm edema due to stenosis of the outflow vein, so balloon-assisted maturation was performed prior to puncture, and cannulation was performed at 2 month after AVG creation. The patient was on normal hemodialysis for about 3 months, but presented with pressure and pain with swelling in the middle part of the upper arm. Ultrasound of the patient's upper extremity revealed a stenosis of the brachial vein, the outflow vein. There was also a collateral vessel upstream of the stenosis that appeared to drain into the biceps muscle. The inside of the muscle was hyperechoic, and the patient complained of severe pain when pressed with a probe. We confirmed the stenosis of the brachial vein with a fisulogram. We performed an anigioplasty with a 6 mm diameter noncompliant balloon on the lesion, which resulted in improvement of the stenosis and reduction of collateral flow. The patient has since shown improvement in pain and pressure.