['The anatomical variations of the extensor carpi ulnaris (ECU) muscle can cause a functional impairment of the wrist and the little finger. The aim of this study was to determine the number, thickness and type of accessory tendon arising from the ECU.', 'The presence of an accessory tendinous slip from the ECU muscle was examined in terms of gross appearance, size, shape, thickness, location and distribution in 54 cadaveric forearms.', 'The accessory slips arising from the ECU muscle were observed in three specimens (5.6%) (two left, one right). These slips ran to the ulnar side of the extensor digiti minimi tendon, originated from the head of the ECU, and ended on the extensor apparatus of the fifth finger. The mean width of the tendinous slips was 1.4±0.01 mm.'] Do accessory tendon slip arising from the extensor carpi ulnaris and its importance for wrist pain?