Of the joints of the body commonly afflicted by serious pathology the knee is the most accessible. Because it is so accessible drastic treatment may be undertaken prematurely and incorrectly. This does not threaten life but may cause permanent morbidity. Dr Stoker has set about examining this joint in depth as a radiologist. As a direct result the surgeon will be helped to make a correct diagnosis and avoid pitfalls, by a diagnostic procedure that is of little inconvenience to a patient. Arthrography is not new but a fresh appraisal is timely. This is not to suggest that there can be any slackening in clinical examination, or that other methods of examination do not have a place. But there are knee joint problems, particularly in teenage girls, in which a clinical diagnosis is very difficult, but must be made exactly. Arthrography must be accepted as a very useful method of examination of the knee joint and an essential one in certain circumstances. More radiologists should be interested in undertaking this examination and surgeons should ask for it. E.L. Trickey, F.R.C.S.