The enactment of eBusiness processes requires the effective usage of the existing legacy applications in the eBusiness initiatives. Therefore, technical issues are not enough to drive the evolution of the existing legacy applications, but it is necessary to consider also problems concerning the perspectives, strategies, and businesses of the enterprises. In particular, there is a strict relationship between the evolution of the legacy system and the evolution of the eBusiness process. In order to support this evolution this paper proposes an approach to extract the requirements for a legacy system evolution from the requirements of the eBusiness process evolution. The proposed approach aims to characterize the software system within the whole environment in which its evolution will be performed. It provides a set of parameters that are useful to address technical, process, and organizational issues.