In May 2013, GlaxoSmithKline (980 Great West Road, Brentford, Middlesex, TW8 9GS, UK) established a new online system to enable scientific researchers to request access to anonymised patient level clinical trial data. Providing access to individual patient data collected in clinical trials enables conduct of further research that may help advance medical science or improve patient care. In turn, this helps ensure that the data provided by research participants are used to maximum effect in the creation of new knowledge and understanding. However, when providing access to individual patient data, maintaining the privacy and confidentiality of research participants is critical. This article describes the approach we have taken to prepare data for sharing with other researchers in a way that minimises risk with respect to the privacy and confidentiality of research participants, ensures compliance with current data privacy legal requirements and yet retains utility of the anonymised datasets for research purposes. We recognise that there are different possible approaches and that broad consensus is needed. Copyright © 2014 John Wiley & Sons, Ltd.