Hospitals are adept at capturing large volumes of highly multi-dimensional data about their activities including clinical, demographic, administrative, financial and, increasingly, outcome data (such as adverse events). Managing and understanding this data is difficult as hospitals typically do not have the staff and/or the expertise to assemble, query, analyse and report on the potential knowledge contained within such data. The Power Knowledge Builder (PKB) project investigated the adaption of data mining algorithms to the domain of patient costing, with the aim of helping practitioners better understand their data and therefore facilitate best practice.