A nine-year-old boy, eight months after a laceration, had a mass in the palm which proved to be a false aneurysm of the ulnar artery verified by histological demonstration of a break at one point in the elastic fibers of the arterial wall. In another patient, sixteen years old, blunt trauma caused a true aneurysm of the ulnar artery in the palm which appeared several months after the injury. Histological verification of generalized dilatation of the artery in one segment was demonstrated. Simple excision was successful in both patients.