AbstractThe work described in the paper was developed during a project carried out jointly by the DHSS OR Unit and a hospital department specializing in the management of acute myeloid leukaemia. One of the aims of this project was to develop a methodology for comparing the results of treatment of patients treated in different clinical trials.The standard OR approach was adopted of using a mathematical model of the results of treatment in a trial as a basis for such comparisons. The paper describes how such a model was built for a particular treatment trial and then used to compare the results of this trial with those obtained in another trial. This comparison indicated important differences between the results of the treatment trials.