Diastasis of the ankle joint was associated with extensive ligamentous rupture and resulted from external rotation or abduction injuries at the ankle. It might occur without associated fracture but was more frequently seen in cases of bimalleolar fracture in which there was fracture of the medial malleolus or rupture of the deltoid ligament with fracture of the lower third of the fibula. Thirty patients of diastasis of the ankle joint were admitted and treated by internal fixation with screw and bolt from January 1978 to December 1981. The following results were obtained: 1. The main cause of the injuries was falling from a height and the other causes were slipping down and sports injury in order. 2. The most common type by Lauge-Hansen classification was supination-external rotation type (20 cases, 67%). 3. Partial diastasis of the ankle joint or anterior type was 14 cases (47%) and complete diastasis or total type was 16 cases (53%). 4. In all cases, mixed oblique fibular fracture and medial instability were seen. 5. The good results were achieved in 24 patients (80%).