The analysis of clinical data collected over time can provide important insight into the health care process. Unfortunately, much of the electronic clinical data that exists today is stored in legacy systems, making it difficult to access and share the information. An approach is needed to improve the accessibility of electronic data stored in legacy system databases. In this study, a legacy database is converted into a relational format in the personal computer environment. The impact of such a conversion on query performance is evaluated, and issues that need to be considered when converting a legacy system database are identified.