Extensor hallucis longus (EHL) tendon injuries can occur in taekwondo athletes when performing hyperplantarflexed barefoot kicking exercises. A state of full excursion of the extensor tendon is used to strike opponents in which the metatarsal bone and the proximal phalanx area is in contact with the opponent. The purpose of this study is to examine the incidence of extensor hallucis longus tendon injury in taekwondo athletes.Case–control study.50 Athletes from the Korean taekwondo national team and a control group of 50 healthy subjects.History of sports participation, the American Orthopaedic Foot and Ankle Society (AOFAS) score and ultrasound imaging of the EHL.Difference in the AOFAS scores were noted with the control group at 92.95±9.18, and the experimental group score at 88.45±10.93 (p<0.01). Only one person (one tendon) from the control group demonstrated changes on sonography (2%), whilst 10 subjects from the taekwondo group displayed changes in 16 tendons (20%). EHL thickness of the experimental group (1.52±0.16mm) was greater and the control group (1.46±0.11mm) (p<0.01).Taekwondo athletes have a higher incidence of changes on sonographic imaging of the EHL compared to non-taekwando participating healthy subjects.