It is often required to provide a modeling language that enables the representation of domain-specific problems and concepts. Domain-specific modeling approaches can be applied for that. However, these approaches usually suffer from low dissemination, missing tool support and high design costs. Thus, it might be more reasonable to adapt and extend common standard modeling languages. This research article presents an extension of the common process modeling language BPMN for modeling clinical pathways in the healthcare sector. The extension is designed methodically by application of the extension design method of Stroppi et al. (2011), which was extended regarding to a deeper domain analysis. The domain analysis considers the design of a domain ontology, requirements analysis as well as an equivalence check between domain concept and BPMN concepts. Finally, the evolved extension is compared with the CPmod modeling language of Burwitz et al. (2013) in order to discuss strengths and limitations.