An evaluation of 361 patients with documented anterior cruciate tears was carried out with analysis of mechanisms, symptomatology, physical findings, and limitations. At the time of injury, patients generally heard a loud pop and felt their knee "slide apart" with a subsequent hemarthrosis. Internal tibial rotation was described as the principal mechanism of iniury in 81.6% of the patients. Less than 20% had a triad type injury. A "crossover" test enabled reproduction of the mechanism. On a 100 point scale, those with "no repair" scored a mean of 55.4, direct repairs 56.7, pes transfers 59.6, and modified MacIntosh 88.9 points. The natural course of a patient can often be projected. A Continuing comparative study of results from treatment regimens and procedures is indicated.