It is widely expected that the Electronic Health Record (EHR) will become an important tool for healthcare professionals when delivering care. The use of this tool will not for long be optional, it will become a professional responsibility to use this tool when appropriate. Until now the focus in the design and implementation of the EHR is on its real-time behaviour. In this paper it is argued that there is a need to be able to reproduce the EHR as it would have presented itself to a specified health care professional at a specified point of time in the past (a "time-machine"). This to be able to assess whether the behaviour of the health care professional was appropriate in view of the data he did retrieve or could have retrieved from the EHR at that point in time. Next the consequences of the implementation of such functionality are explored, these are found to be huge. It would require substantial investments to implement this functionality. So it is important that clarity is created on the need for this time-machine. The professional associations involved and the bodies responsible for the quality of care have to be involved in further discussion on this issue. IMIA might take the lead. Because implementation of the time-machine would have consequences for any information system that contributes in real-time to the EHR, it may well be that the need for this functionality will affect the current common opinion that medical patient data should remain stored in the information systems of the health care establishments where the data were generated and be requested from these systems by the virtual EHR when needed. Uploading medical patient data from the operational systems in the health care establishments to medical data repositories could reduce the number of systems affected considerably.