In medical research and clinical work, having direct access to a large knowledge base of information about patients is very useful. Software for information visualisation can help the user browse, analyse and learn from such knowledge, thus providing new insights and accelerating research. However, when introducing new software to clinicians, who may have limited computer knowledge, adoption can be hindered by the complexity of the applications and the time investments necessary to learn them. By involving clinicians directly in the design process, we have developed mVisualizer, an application that provides a hands-on workspace to visualise and explore patient data. mVisualizer was designed for accessibility and simplicity, and to encourage users to explore the data in order to make discoveries and pose new questions relevant for knowledge gathering and research. The user-centered approach helped ensure that mVisualizer is understandable and easy to learn for clinicians. The application is in use by clinicians today, and its use has led to new discoveries and theories that will be the subject of future medical research. This leads to the conclusion that information visualisation software for exploring patient data can help clinicians and researchers by making the data more accessible, which stimulates research and learning.