Increased anterior laxity was demonstrated in 7 patients (1 in group B and 6 in group C). In the same period these injuries occurred, acute ACL rupture was diagnosed in our region in 16 patients. The proportion of overlooked ACL ruptures to injuries interpreted as a first-degree sprain and to total number of ACL ruptures sustained during the same period was at least 7 out of 54 (13%) and at least 7 out of 23 (30%), respectively. The subjective symptom score was higher and Lysholm's and Tegner's scores lower in the patients with increased anterior laxity compared to the patients with no increased anterior laxity. We conclude that ACL rupture may be overlooked in a rather high proportion and that the 4-5 years' result in such injuries is poorer than in those without increased anterior laxity.