Objective To investigate the effectiveness of groin flap with external oblique aponeurosis in repair of tendon and skin defects of dorsal foot. Methods Between October 2016 and January 2020, 12 patients with compound tissue defects of the dorsal foot caused by trauma were treated. There were 9 males and 3 females, with a median age of 42 years (range, 32-65 years). The size of the skin defects ranged from 8 cm×5 cm to 12 cm×8 cm. All wounds were accompanied by extensor tendon injury, including 6 cases of extensor hallucis longus tendon defect, 5 cases of extensor digitalis longus tendon defect, and 3 cases of extensor digitalis longus tendon and extensor digitorum brevis defects. The interval between injury and admission was 1-6 hours (mean, 3 hours). After admission, the wounds were thoroughly debrided, and the groin flap with external oblique aponeurosis was used to repair the skin and tendon defects in the second stage. The size of skin flap ranged from 10 cm×6 cm to 13 cm×9 cm, and the size of the external oblique aponeurosis ranged from 5.5 cm×3.0 cm to 8.0 cm×5.0 cm. The wounds at donor sties were sutured directly. Results All flaps survived completely without significant complications. All incisions of the recipient and donor sites healed by first intention. All patients were followed up 16-24 months (mean, 18 months). The flaps were satisfactory in appearance and soft in texture. At last follow-up, 9 cases were excellent and 3 cases were good according to the American Orthopaedic Foot and Ankle Society (AOFAS) metatarsophalangeal-interphalangeal joint scale criteria. The toe function was satisfactory. The line scar was left without hernia or other morbidity on the donor site. Conclusion The groin flap with the external oblique aponeurosis can repair the tendon and skin defects of the dorsal foot, with concealed donor site, easy dissection and adjustable thinness, as well as the enough tough aponeurosis.