In comparison with injuries sustained in adult life, ruptures of the fibular ligaments before growth is complete are more frequently characterized by chondral, osseous and periosteal loosening, which was seen up to the 14th year of age in about 50% of our own population of 129 patients up to the 16th year of life. The average age of patients with osseous and chondral lesions was clearly lower than that of those with periosteal injuries, which was lower than that of patients with inter-ligament ruptures. Accidents at school and during school sports classes were the most frequent cause, being involved in more than 50% of cases; of the various kinds of sport engaged in soccer was the most frequent cause, accounting for 28.8% of all cases. Manual examination of ligamentous stability compared with the opposite side by roentgenoscopy without anaesthesia has proved its worth for a definite diagnosis in fresh injuries. In all cases of evident ligamentous instability operative treatment was indicated, with subsequent immobilization with a plaster cast for 6 weeks. Stable healing of the ligament and a good functional result in all cases as well as a very low rate of complications vindicate this management. Conservative therapy, especially in the age group with normally high activity levels, is now considered correct only in exceptional cases or when operative treatment is refused.