Web-enabled databases developed in the late 1990s to help organise large web sites and allow data capture via browser-based forms. By enabling users outside a closed network access to a central database, they permit greater flexibility than traditional 'client-server' systems. Accordingly, web-enabled databases introduce a new tool for epidemiologists, permitting direct data capture at source and thus avoiding many of the delays and errors arising from paper forms and manual data entry. In addition, real-time data collection permits sophisticated decision support and reporting, and thus improved project co-ordination and participation. Nevertheless, the technology is complex and the development of a web-application requires an attention to information technology project management equal to that of the scientific trial or investigation. The potential and problems of web database applications are illustrated by a bespoke system ('PathMan') developed by the Veterinary Laboratories Agency of the United Kingdom Department for Environment, Food and Rural Affairs to manage a large multi-site study investigating the pathogenesis of bovine tuberculosis in England and Wales.