The advance in genome sequencing and high-density DNA microarray technologies is transforming the field of biology into an information-processing science. Analysis and sharing of large volumes of data call for new computational tools that few envisioned a few years ago. Of central importance is a database that, at the minimum, facilitates collection, storage and retrieval of biological data. We have designed and developed a database to store and process data obtained from yeast genome monitoring experiments. This database relies on an Oracle database management system running on a Windows NT workstation. We have also developed web-based applications that provide a flexible and friendly interface to the database. Thus, using a web browser, a researcher can upload raw data from microarray experiments to the database, perform various types of data analysis, and more importantly, store the results back into the database to allow higher levels of data analysis. The features of the database also include graphical viewing of gene expression data, clustering analysis, functional categorisation of genes and a search engine that allows user to quickly find and download the expression information for selected genes in selected sets of samples.