Many UML CASE tools allow software engineers to draw diagrams and generate code skeletons from them. But often advanced users want to do more with their UML models, e.g., apply speciic design patterns, generate code for embedded systems, simulate the functional and non-functional behavior of the system, run validation tools on the model, etc. which a r e v ery diicult to do with the scripting facilities ooered in most UML case tools. In this paper, we describe UMLAUT, a freely available UML Transformation Framework allowing complex manipulations to be applied to a UML model. These manipulations are expressed as algebraic compositions of reiied elementary transformations. They are thus open to extensions through inheritance and aggregation. To illustrate the interest of our approach, we show h o w the model of an UML distributed application can be automatically transformed into a labeled transition system validated using advanced protocol validation technology.