This paper presents a method and concepts of a supporting tool for rapid prototyping of large-scale business information systems. Our method is based on the following guidelines: (1) small team of highly skilled members with combined skills, (2) prototype-based development of subsystems and the system as a whole, (3) brainstorming sessions always involving system analysts, database and application designers, and user representatives (if needed), and (4) application generator pro-viding for efficient prototype development by maximum automation of all design phases. The also presented application generator (AppGen) is based on standardization of functional and visual characteristics of an application, a library of high-level, coarse-grained components, and a set of rules for model-to-application mapping enabling automatic application reconfiguration in case of changes in the data model.