The recent progress of Electronic Music Distribution creates a natural pressure for fine-grained musical metadata. This metadata is needed to provide music distribution services which are able to cope with the mere size of music catalogues, and the desire of users to access music titles by similarity. In this context, we describe a project of a global music title metadatabase, and focus in the particular "genre" descriptor. We analyze existing taxonomies of musical genre as found in the music industry and on the Internet, and stress on their inconsistencies. We describe a novel music genre taxonomy based on a few guiding principles, and report on the process of building this taxonomy.