The proposal is to develop an experimental prototype of a DRR-supported Resource Facility in Simulation Analysis in the field of Mass Transport and Exchange. The suggested governing principle is that a Resource Facility might specialize in a few topics and develop a particular set of simulation technologies which would be of general utility for other such group efforts. The particular features envisaged for this resource are: (1) the development of the simulation systems, SIMCON and SAAM, which represent two rather different types but are both oriented toward interactive development and control of the modeling process; (2) the development and testing of a limited group of optimization techniques for fitting models to data; (3) the development of graphics techniques for displaying the results of simulation analysis; and (4) the development of microprocessorbased terminals for simulation and graphics interfaces. The application areas encompass three major projects, each with various ramifications and collaborations with faculty in other institutions. These are: (1) transport of hydrophilic molecules in the microvasculature, (2) simulation analysis for estimation of tracer uptake and deposition in cells as indicators of regional flow and cellulur function, and (3) analysis of lipoprotein kinetics. The project involves faculty in Bioengineering, Computer Science, Biostatistics, Mathematics, Medicine, and a large number of collaborators inside and outside the University. The developments of SAAM are in collaboration with Dr. Mones Berman of the Laboratory of Theoretical Biology at NIH.