Combining medical decision theory and epidemiologic information, the authors have developed a strategy to assess diagnostic technologies. For any patient, patient utilities with new diagnostic information are compared with the preferred fallback action absent that diagnostic information. After determination of whether the expected value of diagnostic information (EVDI) justifies its cost, the method adds across the eligible population to determine whether the global EVDI justifies the technology's deployment, employing a screen (Hurdle 1) that assumes that the diagnostic device has perfect accuracy. This preliminary evaluation relies on published data on treatment efficacy, population probabilities of illness, etc., but not on new clinical trials. If the technology is not sufficiently cost-effective, even with this optimistic assumption, the strategy recommends against its use. Otherwise, the next step is Hurdle II, in which the critical clinical studies, identified by the decision-theory model, are undertaken. These commonly include measuring the actual diagnostic accuracy of a device, with which the cost-effectiveness is recalculated. These studies in general do not require randomized controlled trials.