Abstract: The usual procedure employed in the analysis of microarray data typically involves little more than a desktop workstation and a spreadsheet program. However, managing data in the form of spreadsheet files is not convenient, particularly when submitting results to public databases prior to publication. In addition, many researchers are discovering that data coming from the latest generation of microarray chips, which may contain many tens of thousands of gene probes, cannot be processed even with the most powerful personal computer. A further deficiency is that normally there is no provision for the systematic recording of information related to the experiment themselves, e.g. platform design, sample hybridization or protocols; such data are critical in checking reproducibility and for comparing with other experiments. Motivation for a more sophisticated and rigorous approach to microarray analysis data has come from researchers in the Hormone Responsive Breast Cancer Network (HRBC, http://www.hrbcgenomics. net/ ), where the analysis and sharing of microarray data with other members of the project, as well as comparison with relevant data in public repositories, are essential requirements