The National Library of France - the Bibliothèque nationale de France (BnF) is hosting a three-year research programme focusing on preserving audiovisual and multimedia documents. The results should help define and guide the preservation policy for the Auduivisual Department. Starting in 2007, the research programme is looking at the composition of 78-rpm records. These discs, considered to be "stable", are in fact little understood, and the are no guarantees as to their long-term preservation - some degradation can in fact already be seen in the BnF collection, one of the largest in the wolrd with about 300,000 items. The research programme thus has a clear goal of anticipating and preventing damage ; it should give an idea of when problems are likely to arise in the preservation of the discs, and the best way to respond.