A comprehensive current survey of the overall incidence and cost of professional medical liability claims and cases does not exist. Over the past five or six years a number of partial studies and articles have been published but the dissimilarity of the data makes more than a rough correlation of these impossible. The Law Department of the American Medical Association is presently undertaking studies that should aid in broadening our understanding of medical, legal, and insurance aspects of professional medical liability, but these are not as yet available. This is not to say that we are in complete ignorance. We can use the facts that are known and from these draw inferences that are likely to be valid. While they may not be perfect, they can be used as guides to conduct and action. An instance of this process is to be found in a brief study of closed professional liability insurance claim files involving radiation therapy. It is to be emphasized that none of the observations and conclusions are medical ...