We present a case of a healthy 52-year-old man who came to our clinic because he suffered fatigue in the upper left limb during the past 4 months. Progressively he developed claudication with minimum efforts and nocturnal pain that awoke him, tingles, coldness and pallor in the whole hand. Cervical, shoulder, elbow, and wrist mobility and muscle power were normal. There was absence of left axillary, humeral, radial and ulnar pulses, with a left subclavian pulse present. Echo-Doppler and CT angiography revealed axillary and brachial artery thrombosis secondary to a narrow left intercostoscalenic space due to agenesis of the first ribs? anterior arch and synchorosis of the costal remnant with the second rib. The first two ribs were resected, and an axillary artery endoprosthesis and an axillary-radial bypass were implanted, achieving adequate distal reperfusion. Eight months later, the patient has no pain and is asymptomatic.