ACL injuries in children and adolescents have increased substantially in recent years. Nevertheless, treatment algorithms are domiated by predjudice more than by evidence, eventhough the scientific basis, summarized in this paper, is sound. The likelihood of an ACL tear in a traumatic hemarthros, even without contact, is 52%. More than half of the cases show concurrent injuries. Methods and criteria for success of conservative treatment are published in detail, however, surgical treatment produces a better clinical outcome in most cases. Various surgical techniques exist, and age appropriate treatment can elimate the risk of a growth disturbance and restore the normal function of the knee.