Advances in medical image analysis have increased the need to integrate and deploy image analysis software in daily clinical routine and in epidemiological studies. We developed a Distributed Workflow Management System (DWMS) that supports a wide portfolio of image analyses in different CT and MRI application domains. The DWMS supports software components for image import/export, caching, processing and notification that are distributed on a heterogeneous grid of commodity computers. Communication between the components is performed by exchanging SOAP messages on request of standard compliant Web services. The workflows are executed fully automatically upon receipt of the medical images. After processing, the results are routed to a workstation for review and further analysis or to an image archive (PACS). A web-based monitor shows the status of running, pending and terminated workflows. The DWMS improves the interoperability between image acquisition devices, clinicians and researchers by making image analysis applications available in a transparent way, which accelerates the uptake of new research techniques. Through distributed computing, the workload is balanced and results can be obtained quicker. As the availability is guaranteed at a 24/7-hour basis, the system provides a reliable and completely automated solution for demanding image analysis tasks in a multi-vendor environment.