Pharmacogenetic testing can prevent adverse drug events but has rarely found its way into clinical routine. One reason is the lack of tools for smooth and automatable integration of pharmacogenetic knowledge into existing processes. Especially, electronic medical records (EMR) represent a suitable environment for such tools. We developed a modular service-oriented prototype of a pharmacogenetic decision support system within an EMR system of the Bern University Hospital. Here, we present the component architecture of our system and discuss issues required for generalizing our results.