A patient oriented hospital information system (ARIANE) was inaugurated at the Sherbrooke University hospital (CHUS) in 1990 and a clinical data warehouse (CDW) completed 2004. The CDW is updated from ARIANE every 24h and includes ICD discharge diagnosis data, visit DRG and SNOMED encoding. The data is encrypted on storage. Data is accessed according to institutional approval. To facilitate data access two levels of tool have been made accessible using a web-browser. The first level consists of a 'dashboard' that has a defined design and enables a set of pre-determined dynamic queries about a patient population. This level can be operated with minimal training. The second level uses a convivial database query tool, which requires some prior training. Two prototype dashboards have been designed and evaluated for acceptability. The first for the emergency department enables analysis of patient occupancy. The second for the biochemistry department enables quality assurance evaluation. In most cases worldwide the clinical data warehouse is only beginning to be exploited, often impeded by lack of connection between different enterprise databases. Our CDW is expected rapidly to create a culture change so that clinical practice can be continuously evaluated using compiled data readily available from the electronic health record/hospital information system.