Although a pharmacoeconomic model is usually created for one setting, there is often interest in using it in other jurisdictions. This requires that it be modifiable by other users, and given the complexity of most models, this may be difficult to do. OBJECTIVE: To develop a low cost tool that standardizes model inputs and outputs and allows models to be easily edited and analyzed. METHODS: An electronic viewer (MODEL-IT(r)) was developed as a "container" that allows display and interaction with disease models. The tool is programmed to work as a stand-alone application in a Windows(c) environment. It is designed to read any model that has been formatted according to a simple set of rules. The model engine itself can be in any format, including EXCEL. The screens were developed to maintain a consistent format yet be able to display inputs and outcomes pertinent to the specific model. Tool functions are accessed by self-explanatory buttons. RESULTS: MODEL-IT(r) classifies inputs into specific categories including population characteristics, disease parameters, model controls (e.g. number of replications), treatment details and costs. All fields are editable. Outcomes are model-specific but are also classified into costs, effectiveness, survival and cost-effectiveness. Model versions can be saved for later use, and all screens can be printed or exported to other programs. Model documentation can be incorporated as a help file. The Model-IT(r) viewer is available free of charge. CONCLUSIONS: A viewer has been developed to allow users to interact with models in a standard format and to increase interdisciplinary access and understanding of models in order to support their wider use in decision-making about new pharmaceuticals.