The French Action Spécifique Observatoires Virtuels has created the Workflow Working Group in 2005. Its aim is to explore the use of the Workflow paradigm in the astronomical domain. The first consensus was the definition of a Workflow as a sequence of tasks realized in a controlled context (at various levels: intelligence in the choice of the algorithms, flow control, etc.), based on use cases studies, in an architecture which takes into account VO standards. The current roadmap is to provide scientific use cases in several domains (image, spectrum, simulation, data mining, etc.) and to improve them mainly with VO existing tools. Another important point is to develop collaborations with the IT community (links to EGEE, ...). Use cases are useful to compare the pertinence of the possible workflow models and to understand how to implement it as efficiently as possible with the existing tools (ex. : AstroGrid, A\"IDA, WebCom-G, etc.). The execution (local machine, cluster, grid) through this kind of tools and the use of VO functionalities (Web Services, Grid, VOSpace, etc.) becomes almost transparent.