In spite of its scientific interest, which is to throw light on a large part of the mediaeval and modern past of a small town in the south-east of the Oise, this publication is in itself a challenge which mirrors the approaches, the conditions and the limits of an undertaking of more than thirty years standing. The results of the excavations at the Clunisian priory of Nanteuil-le-Haudouin are set out here as part of an exhaustive documentary and historical study supported by a series of specialised analyses. The church, better preserved, provides valuable evidence for datation, reliable fixed points in a complex evolution. The prioral buildings, which are more fragmentary, are analysed in their structure. The outside burial areas, adjacent to the buildings, are studied in detail. Finally, the immediate surroundings of the priory, as integral parts of the monastic complex, are not neglected: gardens, wells, terrace, annexes or those buildings reserved for the familia. Finally, this monastery has been replaced in its socio-political context, with the castle, in its urban context with the market town, and in its religious context with the chapel of Les Marais and the priory of Autheuil-en-Valois. Traduction : Margaret & Jean-louis CADOUX.