Abstract. We developed the Nested Relational Sequence Database System (NRSD System), which is built upon the Nested Relational Sequence Model (NRSM). The NRSM eliminates a substantial amount of redundancy embedded in XML documents and preserves the order of XML data. In this paper, we demonstrate that the storing and querying of XML data are desirable over an NRS relation, which we incorporate an index system into the NRSD System. We introduce a set of NRS operations which allow users to manipulate the XML data effectively and demonstrate how to use NRS operations to query the XML data stored in the NRSD System. Our experimental results confirm that the NRSD System substantially reduces the storage size of data. We also study the performance of the select and project operations having path expressions at different nested levels.