The Lachman test, a method allowing to verify a lesion of the anterior cruciate ligament, is not yet generally known, but it is considered to be the only test which provides clear evidence. A radiological check of this test performed by us with a special holding device proved its high qualitative and quantitative value. The possibility to diagnose also lesions of the posterior cruciate ligament could be demonstrated. A special template has been developed for a rapid reading of the test results. The test is particularly suited for the examination of fresh lesions of the knee joint without anesthesia, for the follow-up of surgical transposition of ligaments, and for the elaboration of medical expert opinions.