The rupture of the lateral ligament of the ankle is a common injury in young active people. Accurate defining of the anatomical site and severity of injury gives crucial guideline in decision of treatment modality. In general, techniques used to demonstrate repture of the lateral ligament include the stress-inversion radiograph, the anterior drawer test and arthrography of the ankle. In particular, arthrography may be useful in the demonstration of the injury of the ligament around ankles, especially the inferior tibiofibular ligament and ascertaining if a lesion is old or recent. But arthrography has several disadvantages: false negative results due to prevention of leakage of contrast medium by clot or hematoma formation on ruptured site, false positive interpretation due to normal communication of the adjacent tendon sheaths with the ankle joint, difficulty in differentiation between tears of the anterolateral and posterolateral ligaments. To overcome these problems of arthrography, authors analyzed arthrograms of 105 ankles(77 sprained ankles, 28 control ankles) in seventy-seven patients and obtained results as follows: l. Among the 105 cases, traumatic leakage of contrast mediun was observed in 47 cases and normal finding in 58 cases. 2. In 21 (36.1%) of the normal arthrographic findings without traumatic leakage, leakage of contrast medium into adjacent tendons and subtalar joint was seen. Contrast medium entered the tendon sheaths of the flexor hallucis longus in 17 (29.3%), flexor digitorum longus in 7 (12.1%) peroneus tendons in 1 (1.7%) and subtalar joint in 4 (6.9%). 3. In 28 (59.6%) of the 47 cases of traumatic leakage of contrast medium, escape of contrast meduin into the adjacent tendons and subtalar joint was seen. Leakage of contrast medium to the peroneal tendon sheaths was seen in 20 (42.6%) flexor hallucis longus in 4 (8.5%) and subtalar joint in 8 (17.0%),4. Among the 47 cases of traumatic leakage of contrast medium, anterior talofibular ligament was torn in 19, middle calcaneofubular ligament in 4, and both anterior talofibular and middle calcaneofubular ligament in 24.5. Surgical exploration of the 30 ankles in 47 cases of traumatic contrast leakage was made. In all cases which have shown extraarticular contrast leakage into the peroneus tendon sheaths, ruptures of calcaneofibular ligament was confirmed on surgical finding. 6. Localized leakage of contrast medium through torn calcaneofibular ligament was well visualized on stress-arthrogram and anterior talofibular ligament on external oblique projection. 7. Stress-arthrogram may decrease incidence of false negative interpretation due to hematoma or clot formation on rupture sit and hydrodynamics.