In recent years the massive reductions in the incidence of gross nutritional deficiencies and ability to control most severe infectious diseases have shifted the focus of nutrition research to determining the intake of various nutrients needed to provide optimum health over a life- time. However, there are Ongoing controversies about the best methods of assessing the requirements for a variety of nutrients. There is also controversy about assessing nutritional status at all stages of life. These problems present a significant challenge which will require improved research techniques. Mathematical modelling is one such technique. It provides information about metabolic rates and fluxes, which may be better indicators of nutritional status than some of the more traditional parameters. It also provides a means of simulating responses to a variety of conditions. This can be valuable for testing the model as well as for designing experimental protocols. The conference proposed here for May 8- 11, 1994 in Fort Wayne, IN will be the 5th in a series of meetings started in 1985 to encourage the use of mathematical models in nutrition research. The first day will be devoted to workshops for beginners and experienced users of the Simulation, Analysis and Modelling program (SAAM) developed by the Laboratory of Mathematical Biology at NIH. The second day will deal with modelling vitamin metabolism and protein turnover. The third day will cover some general analytical and mathematical approaches to modelling whole body processes. The final day will deal with introducing some of the newer in vitro techniques which might be applicable to obtaining kinetic data in nutritional studies. PC, RISC and VAX computer facilities will be available to participants throughout the meeting. Poster facilities will be available for voluntary papers.