The World Health Organization initiated the project "High5s - Action on Patient Safety". The aim of the High5s project is to achieve a measurable, significant and sustained reduction in the occurrence of five serious patient safety problems within five years, in five countries. One of these patient safety issues is medication reconciliation - the process of assuring medication accuracy at transitions of care. In Germany, eleven hospitals are currently implementing medication reconciliation. Medication reconciliation represents the systematic comparison of the current patient's medication list with the medication list in hospital. For this purpose, Lead Technical Agencies of each participating country translated and adapted the standard operating procedure. This standard operating procedure describes the implementation and the procedure of the medication reconciliation process in detail. This process is divided into three parts. First, the best possible medication history is recorded. Second, based on those records, the responsible physician subsequently prescribes the medication. In the third step, the best possible medication history is compared with the medication orders at admission. During this process, it is likely that some discrepancies will occur. Such discrepancies are discussed with the responsible physician and clarified. A comprehensive acquisition of the best possible medication history is thus particularly important. It will be part of medical records throughout the patients' hospital stay. Thus it will be used as an additional source for comparison and adjustment of patients' medication in order to facilitate optimal drug treatment during the entire hospital stay. The practical implementation of medication reconciliation requires extensive change of the current prescription sheets or prescription software. Thus, this provides a great challenge for many hospitals. Nevertheless, in the Netherlands it has been shown that it is possible to prevent 90 % of unintentional discrepancies with medication reconciliation. A German hospital recently showed a reduction of discrepancies by about 77 %. The use of medication reconciliation to improve clinical endpoints is currently subject of further studies.