Ulnar impaction syndrome is a common source of ulnar-sided wrist pain. It is a degenerative condition that occurs secondary to excessive load across the ulnocarpal joint, resulting in a spectrum of pathologic changes and symptoms. It may occur in any wrist but is usually associated with positive ulnar variance, whether congenital or acquired. The diagnosis of ulnar impaction syndrome is made by clinical examination and is supported by radiographic studies. Surgery is indicated if nonoperative treatment fails. Although a number of alternatives exist, the 2 primary surgical options are ulnar-shortening osteotomy or partial resection of the distal dome of the ulna (wafer procedure). This article discusses the etiology of ulnar impaction syndrome, and its diagnosis and treatment.