Unilateral ischemia of hand digits is usually caused by thoracic outlet obstruction, arterial emboli from a cardiac source, or atherosclerosis. The case of a metal press worker with unilateral ischemia due to hypothenar hammer syndrome, a condition caused by the repetitive use of the hypothenar eminence as a hammer with resultant damage to the ulnar artery, is described. Most such patients present with unilateral ischemia in the ulnar artery distribution of the dominant hand. This patient had used both hands repeatedly to pound the edges of large steel plates and presented with nondominant-hand ischemia, but was found to have the syndrome bilaterally by angiography. The distinctive features of this syndrome, a preventable and treatable cause of digital ischemia, are emphasized.