Dynamic aspects of workflow execution require flexible solutions. Especially in an interorganisational context many variable factors can only be determined during the actual execution of a workflow. These factors may require contextual, local changes within a process in order to adequately support and represent the real-world scenario. This paper describes the agentworkflow approach, which uses a combination of the agent and workflow concepts to address a number of challenges of workflow execution. Both agents and workflows are provided as high-level Petri nets. The focus of this paper is the flexibility aspect of this approach. Agent-workflows allow the dynamic reconfiguration of the workflow specification. The key to this is the exchange of subworkflows depending on the changing circumstances of the workflow execution. This allows the workflow system to adapt to these circumstances and support users adequately.