The ELVIRA system is a tool to construct model based decision support systems. The models supported are based on probabilistic uncertainty. We are working to obtain our first stable version of Bayesian belief networks with discrete and continuous variables. The ELVIRA system has an easy to use Graphic Interface User (GUI) which allows you to define models clicking your mouse. But, if you wan’t use it, you can edit the ASCII format of the ELVIRA system to introduce your models. ELVIRA has been programmed only with the JAVA language. So, you can use it on any operating system. Current version support Bayesian Networks and Influence Diagrams with discrete variables. It have methods to inference, learning, abduction and making decision.