Aneurysmal degeneration of the ulnar artery is a rare cause of digital ischemia, which is usually described in workers exposed to repeated trauma over the hypothenar eminence, due to a relative lack of artery protection at this level. Hypothenar Hammer Syndrome (HHS) is most commonly found in men who are exposed to repetitive palmar trauma in one or both of their hands for years due to their occupation. The ulnar artery, after penetrating the hand through the Guyon’s canal, continues superficial to the hypothenar muscles, only covered by the palmaris brevis muscle, the palmar aponeurosis and the skin. In this area of scarcely two centimetres, the artery is stretched over the hook of the hamate bone, which acts as an anvil and contributes to its injury after prolonged repetitive trauma. Mural degeneration with intimal injury occurs which results in thrombosis, and/or medial injury, leading to the formation of true aneurysms. Acute ischemia, atheroembolism and neurologic compression are the most common complications, though not rupture. Some authors have suggested that trauma is not the only cause of the syndrome, but arterial fibrodysplasia is partly responsible for aneurysmatic degeneration. Digital perfusion is assured by two arterial trunks, ulnar and radial, which meet in the superficial and deep palmar arch. The coexistence of hypoplasia of the radial artery and an ulnar aneurysm, without precedent in the medical literature, makes management of the injury important since there is only a single arterial supply to the hand.