A 44-year-old patient with type I diabetes with critical upper limb ischemia of the left hand was referred to our department with ischemic tissue loss and rest pain. After unsuccessful use of the endovascular antegrade approach, retrograde revascularization with percutaneous transluminal angioplasty (PTA) of the ulnar artery and the Palmar arch through the radial artery was successfully performed (the radial to ulnar artery loop technique). Relief of the patient's symptoms was immediate and ischemic lesions were healed at 6-month follow-up. This technique, which has been used for the first time in critical upper limb ischemia, may significantly increase the success rate of percutaneous angioplasty, especially when antegrade recanalization fails.