Efficacy and costs of the diagnostic process have been under extensive investigation for a long time. In this study we present a detailed, retrospective analysis of the clinical and economic aspects of 347 diagnostic admissions in a teaching hospital. We have, furthermore, investigated the clinical history of a group of 50 patients, from the beginning up to one year after definitive diagnosis, through a structured questionnaire. The results shed some light onto efficacy, cost-effectiveness and cost-profit balance of diagnostic admissions. Strategies to improve efficacy and cost-effectiveness are discussed.