XML has emerged as the standard for information representation over the Internet. It is critical to store and query XML data to exploit the full power of the new technology. However, most enterprises today have long secured the use of relational databases. Thus, simply replacing relational databases with a pure XML database is not a good choice. It is thus crucial to map XML data into relational data. This paper studies the performance evaluation of storing XML documents into relational databases and identifies which mapping approach is best suited for which business environment. The performance results for all approaches are presented and a number of interesting results obtained from these evaluations are highlighted.