Rendering expressive music performances involves complex processes that constitute a challenging research area for computer music research. Besides, it is a rich ield for investigating aspects of human intelligence, emotion, and creativity. Case-based reasoning is one of the AI techniques that have produced more promising results in rendering expressive music performances. Furthermore, it has advanced the state of the art in case-based reasoning through the invention of new approaches to case representation, case retrieval and case reuse adapted to musical knowledge. In this talk Lopez de Mantaras will describe in some detail two successful case-based reasoning systems applied to expressive music performance that have been developed at the Artiicial Intelligence Research Institute.