In this thesis, Barbara Borkent presents the results of the PROTON study. PROTON is a (Dutch) acronym for PROfiles of TransfusiON recipients. The aim of this study was to describe the distribution of blood products over various patient groups in the Netherlands. Quantitative information on recipients of blood products issued to hospitals is needed to assess the cost-effectiveness of blood safety interventions. The health benefits of such interventions are achieved in transfusion recipients and thus depend on their profiles: age, gender, life expectancy after transfusion, hospital diagnosis, and number and type of blood products received. Twenty hospitals in the Netherlands provided information on blood products transfused between 1996 and 2006, resulting in the first national dataset containing characteristics of blood product recipients in the Netherlands. This dataset was used to describe the profile of the Dutch transfusion recipients. The results were used to analyze the cost-effectiveness of a number of tests for blood-borne viruses and to predict future demand and supply of blood products