Metadata has the proven ability to provide information necessary for successful long-term curation of digital objects. However, without curation metadata itself may deteriorate in terms of its quality and integrity over time. Therefore, a digital curation process needs to incorporate the curation of metadata along with that of data in order to ensure the accurate description of data over time. Unfortunately, no comprehensive method for effective curation of metadata for long periods of time is known to exist at present. Even the Reference Model for Open Archival Information System (OAIS), despite being the most comprehensive and widely adopted framework for long-term data preservation, fails to address the requirements of long-term metadata curation in a comprehensive and unambiguous manner. This paper presents an approach to efficiently curating digital metadata over the long-term that is achieved through articulating the metadata curation related ambiguities of the OAIS Reference Model. The approach essentially involves the use of a “Metadata Curation Model”, which is a specialised edition of the “Data Management” module of the OAIS Reference Model, dedicated to the purpose of long-term metadata curation.