As the number of non-expert database users who wish to access genome databases directly grows, it becomes increasingly imperative to develop an easy-to-use query interface for such databases. Relying on a graphical solution is one way of addressing the problem. A graphical query interface provides a built-in schema browsing mechanism, which enables users to express queries more easily than with a textual query interface. In this paper, we summarize our experience of building a graphical query interface for ACeDB genome databases. ACeDB is a pseudo-object-oriented database system which was primarily developed to store biological data and to be used by biologists. Our interface, entitled Xyntagma, allows the user to browse an object-oriented schema and enables him to graphically express ad hoc queries that conform to the ACeDB query syntax.