Optimal design of procedures and protocols for screening blood and blood products for human immunodeficiency virus (HIV) is dependent on consideration of seroprevalence in the donor population (acknowledging that there are significant regional differences), on the prevalence of and overlap with other markers such as those for hepatitis, and on voluntary self-deferral overlap with other markers such as those for hepatitis, and on voluntary self-deferral behavior under different contingencies. This project is to explore the feasibility of incorporating these variables and their interactions into a computer-based decision support package for the blood banking community, in order to assist in the estimation of the economic, legal and policy consequences of current vs. alternative screening protocols for HIV in donated blood. In addition, such alternative protocols are to be oriented to even further increasing the safety of the blood supply while minimizing donor attrition. If the parameters for a decision-prompting model to simulate the effects of alternative screening procedures can be identified and documented during Phase I, we will propose a phase II venture for the development of an appropriate software package.