Vascular injuries associated with arthroscopic surgery of the knee are uncommon. Pseudoaneurysm of the medial inferior genicular artery after hamstring tendon ACL reconstruction has not been reported yet. Diagnosis can be obtained clinically if continuous filling of the drain, hard and painful swelling of the lower leg, pulsatile swelling or mass in the region of the affected joint, are present. Definitive confirmation of the diagnosis can be achieved by sonography and angiography. The method of treatment consists of simple surgical wound exploration and ligation of the affected vessel.