We describe a method involving user-system simulation to drive rapid development and evaluation of layout, organization or information technology in healthcare. The method has been developed, tested and refined in three sub-projects in the Capital Region of Denmark. The overall goal of the project was to validate such a development method in a two-year project (2010-11). Explorative simulation is primarily based on approaches in design and usability engineering and simulation-based training in healthcare, and involves end-users and designers or engineers in a collaborative exploration of design solution. A simulation project consists of a number of discrete simulation events that begin with an observation study of the situation or object in question. This is followed by a Framing workshop where end-users (doctors, nurses, secretaries etc.) are guided through a process that uncovers problems, needs and wishes. This is translated into scripted scenarios that are explored in simulations. The simulations all use end-users to play their normal role in the scripts but different types of props are used depending on purpose. E.g. simulation of layout and organization are done using table-top simulation and mobile devices are simulated on iPads with mock-up screens. We describe and exemplify the chief advantages of the explorative simulation method, summarized briefly as follows: - a surprisingly quick way to set up and test a reasonably complex work setting and task environment - an efficient way in which application developers can gain insight into the healthcare work practice and design applications accordingly - Theories and new ideas can be readily transformed to into the simulated world where they are explored and quickly rejected or used further - A very cost-effective approach to innovation.