The Portal of Medical Data Models (MDM) is a multi-lingual repository of medical data models for the scientific community. It contains data models from medical research (clinical studies) and routine patient care (electronic health records). Currently, most information systems in healthcare apply heterogeneous and proprietary data models. Re-use of existing data models and sharing of best practice can foster data exchange and standardisation of medical data models on a national and international level. The University Library of Heidelberg contributes to this project regarding technical, contents and organisational aspects.