The aim of this paper is to present some remarks on computingmaximal consistent extensions of dynamic information systems.Dynamic information systems can be used as a tool for description of concurrent systems. In this case, they include the knowledge about global states and transitions between them observed in given concurrent systems. The task of creating a maximal consistent extension is to find all global states and all transitions between them which are consistent with the knowledge included in data tables representing a dynamic information system. A method for computing such an extension is given. The method presented here seems to be more ef- ficient than methods presented earlier in the literature. Our approach is based on the rough set theory.