There has been little research concerning this muscle since the 1920s, when Hecker described this muscle to be present in (13%) of his dissections of cadaver legs. The purpose of our dissections was to establish the incidence of the peroneus quartus muscle, its origins, and insertions. One hundred and twenty-four legs from 65 fresh human cadavers were dissected under loupe magnification. When the peroneus quartus tendon was found, its origin, insertion, and anatomic relationship to the peroneus longus and peroneus brevis were observed. All specimens were sketched and photographed. The peroneus quartus muscle was present in 27 legs (21.7% of specimens). Its origins, insertions, and size varied. In 17 legs (63%) the muscle originated from the muscular portion of the peroneus brevis, and inserted on the peroneal tubercle of the calcaneus. The peroneal tubercle was hypertrophied at the insertion in most cases. The results of this study in general show that there was much higher incidence of the peroneus quartus muscle than Hecker claimed. Its course, origin, and insertion varied. Its tendon can be used for reconstructive procedures about the lateral aspect of the ankle, especially in anterior dislocation of the peroneal tendons and reconstruction of lateral ligaments.