A retrospective study was conducted to survey the extent of intracapsular damage associated with ACL insufficient knees in both the acute and chronic situation. Previously unoperated knees were studied to assess the effect that reinjury had on the knee joint. One hundred patients with confirmed anterior cruciate ligament damage, both clinically and under general anesthesia, were examined arthroscopically and the findings recorded on video tape. Both anterolateral and posteromedial approaches were used to well visualize the entire intra-articular structures of the knee joint. The incidence of meniscal tears increased from 77% in the acute injury to 91% in the chronically reinjured knee (p less than .06). Furthermore, articular surface disease increased from 23% in the acute injury to 54% in the chronically ACL lax knee (p less than .002). The majority of meniscal tears were medial and amenable to peripheral suture repair (63%). Irrespective of how one approaches ACL insufficiency of the knee acutely, one cannot ignore the likelihood of finding these significant associated lesions. Reinjury to the knee will likely enhance the incidence of meniscal tears and articular changes.