Clinical trials often require large and redundant documentation efforts, because information systems in patient care and research are separated. In two clinical trials we have assessed the number of study items available in the clinical information system for re-use in clinical research. We have analysed common standards such as HL7, IHE RFD and CDISC ODM, regulatory constraints and the documentation process. Based on this analysis we have designed and implemented an architecture for an integrated clinical trial documentation workflow. Key aspects are the re-use of existing medical routine data and the integration into current documentation workflows.