Dynamicity is a recurrent topic in traditional business workow systems. The need and feasibility to perform changes in workow process instances while they are being executed has been a main (and to a long extend yet unsolved) challenge. More recently, the scientic workow domain has also paid attention to this topic and some of the current scientic workow management systems give a certain support for dynamicity. In general, there is a common agreement that dynamicity is an intrinsic requirement for scientic workows, but the understanding about the real needs and functionality to be provided is confuse. This report is mainly focused on contributing to enhance such an understanding by analyzing dynamicity scenarios, requirements and proposals in scientic workows. First, ve general scenarios involving different dynamicity needs are described through the introduction of concrete examples. Then, these scenarios are used to identify a set of dynamicity requirements for scientic workows support. Finally, a review of current well-known scientic workow execution systems is presented, focusing on their proposals to support dynamicity.