The value of xero-radiography for demonstrating injuries to the capsule and ligaments of the knee has been investigated. A tomographic method was used in conjunction with arthrography of the knee. The results have shown that, in vitro, injuries of the cruciate and lateral ligaments and of the capsule are well shown by xero-tomography and that it is possible to evaluate their extent. Simultaneous demonstration of injuries to the menisci is less certain. In order to show these accurately, special methods would have to be employed. Despite the higher radiation dose which must be expected, and the greater complexity of this technique, we consider that a clinical investigation of the method is indicated.