Extensor carpi ulnaris tendon subluxation can be a challenging diagnosis as a cause of wrist pain. The tendon is stabilized by a tough subsheath. This subsheath is vulnerable to tears in acute wrist movements, especially those combining supination, flexion, and ulnar deviation. The patient presenting acutely may experience swelling, tenderness, and pain. In a chronic setting, the complaint is often an unstable wrist. The diagnosis can be made with a thorough examination, and ultrasonography can be used to evaluate the dynamics of the tendon. Surgical repair with a flap of extensor retinaculum to re-create the tendon’s stabilizing subsheath is recommended.