Due to the increasing amount of health information being gathered and the potential benefit of data reuse, it is now becoming a necessity for tools, which collect and analyse this data, to support integration of heterogeneous datasets, as well as provide intuitive user interfaces, which allow clinicians and researchers to query the data without needing to form complex SQL queries. The West Midlands Query Tool consists of an easy-to-use graph-based GUI, which interacts with a flexible middleware application. It has the main objective of querying heterogeneous data sources for exploring patient cohorts through a query builder and criteria set.